4 ms·

Is there anywhere that explains how a traditional electrostatic motor works?

adrian_b 5y ago
For many structures of motors with magnetic fields, there are equivalent structures of motors with electric fields, which you can obtain by replacing each pair of windings that creates a north-south pair of magnetic poles with the 2 plates of a capacitor, which create a positive-negative electric pole pair when the capacitor is charged. For example, you could have a stepping motor where the rotor has 2 metal plates at 180 degrees on the cylinder, and you apply a fixed voltage on them, so that one is positive and the other is negative. On the periphery of the stator, surrounding the rotor, you have 2 or more pairs of metal plates spaced at equal angles. The 2 plates of a pair, at 180 degrees on the stator, are connected together forming a capacitor and you have as many capacitors as pairs. Each stator capacitor will correspond with a phase of the stator. When you apply voltage on one phase of the stator, the rotor will rotate to allign with the plates of that phase (the negative rotor pole to the positive stator pole and similarly for the opposite pole). To advance 1 half step, you charge the capacitor of the next phase and the rotor will move half-way between the plates (being equally attracted by them). Then you discharge the previous phase capacitor and the rotor will move to be aligned with the plates of the next phase, achieving a full-step movement. Applying a sequence of stator capacitor charges and discharges will achieve any movement you want. The same transformation described above for a stepping motor can be done for any other kind of electric motors. Even the permanent magnet motors and the hysteresis motors have correspondents in motors with electrets, but those are unlikely to have so good characteristics as the motors with magnets. In a motor with magnetic fields, if you want to supply the rotor with a current, you need gliding contacts, which have a limited lifetime, and you also have a permanent power consumption. These 2 disadvantages make preferable the induction motors, permanent magnet motors, hysteresis motors or variable reluctance motors, all of which are worse for other characteristics. For a motor with electric fields, the rotor needs a voltage, but the only power loss is due to leakage currents, so the rotor could incorporate a battery to provide the voltage, which could last many years. Unfortunately, the limitations due to electrical discharges make this potential advantage irrelevant, except maybe for use in vacuum outside Earth.
- mrfusion 5y ago
  Thanks. That makes sense.

For many structures of motors with magnetic fields, there are equivalent structures of motors with electric fields, which you can obtain by replacing each pair of windings that creates a north-south pair of magnetic poles with the 2 plates of a capacitor, which create a positive-negative electric pole pair when the capacitor is charged. For example, you could have a stepping motor where the rotor has 2 metal plates at 180 degrees on the cylinder, and you apply a fixed voltage on them, so that one is positive and the other is negative. On the periphery of the stator, surrounding the rotor, you have 2 or more pairs of metal plates spaced at equal angles. The 2 plates of a pair, at 180 degrees on the stator, are connected together forming a capacitor and you have as many capacitors as pairs. Each stator capacitor will correspond with a phase of the stator. When you apply voltage on one phase of the stator, the rotor will rotate to allign with the plates of that phase (the negative rotor pole to the positive stator pole and similarly for the opposite pole). To advance 1 half step, you charge the capacitor of the next phase and the rotor will move half-way between the plates (being equally attracted by them). Then you discharge the previous phase capacitor and the rotor will move to be aligned with the plates of the next phase, achieving a full-step movement. Applying a sequence of stator capacitor charges and discharges will achieve any movement you want. The same transformation described above for a stepping motor can be done for any other kind of electric motors. Even the permanent magnet motors and the hysteresis motors have correspondents in motors with electrets, but those are unlikely to have so good characteristics as the motors with magnets. In a motor with magnetic fields, if you want to supply the rotor with a current, you need gliding contacts, which have a limited lifetime, and you also have a permanent power consumption. These 2 disadvantages make preferable the induction motors, permanent magnet motors, hysteresis motors or variable reluctance motors, all of which are worse for other characteristics. For a motor with electric fields, the rotor needs a voltage, but the only power loss is due to leakage currents, so the rotor could incorporate a battery to provide the voltage, which could last many years. Unfortunately, the limitations due to electrical discharges make this potential advantage irrelevant, except maybe for use in vacuum outside Earth.

mrfusion 5y ago
Thanks. That makes sense.