Brushless synchronous motor control system

Claim 2

In a synchronous motor unit having a stationary winding, a rotating winding, and a discharge impedance adapted to be connected in circuit with the motor rotating winding, and an exciter unit having a stationary winding, a rotating winding and an airgap therebetween, the exciter rotating windinG being electrically connected to the motor rotating winding, the motor unit being operated in a startup mode wherein electrical energy is transmitted from the motor rotating winding to the stationary exciter winding through the airgap and a running mode wherein electrical energy is fed from the exciter windings to the motor rotating winding, a control circuit comprising switching circuit means for automatically connecting the impedance into circuit with the motor rotating winding during the startup mode and out of circuit with the motor rotating winding during the running mode, said control circuit including switching means for sensing the direction of flow of electrical energy across the airgap from the motor rotating winding to the exciter stationary winding and causing said connecting in response to said sensing of said direction.

Claim 3

The control circuit of claim 1 wherein said control circuit is fixedly supported relative to said motor rotating winding.

Claim 4

In the synchronous motor unit of claim 1 further including means for shorting the motor rotating winding during the startup mode, said control circuit connecting the impedance into the short circuit to limit current flowing in the one winding.

Claim 5

In the synchronous motor unit of claim 3 wherein the exciter unit includes a half-wave rectifier, the shorting means being connected in shunting relation with the motor and exciter rotating windings, the control circuit having the impedance connected in series circuit with the motor and exciter rotating windings during one-half cycle of the startup mode and in series circuit with the motor rotating winding and the shorting means during the opposite half-cycle of the startup mode.

Claim 6

The control circuit of claim 4 wherein the switching means is connected in shunting relation with the impedance, the switching means being open during the startup mode and closed during the running mode.

Claim 7

The control circuit of claim 5 wherein said switching means includes a semiconductor switching device having a first and second electrode and a control electrode and a conduction control circuit connected to said control electrode and said second electrode for controlling the conduction between said first and second electrodes in response to the sensing of the startup mode.

Claim 8

The control circuit of claim 6 wherein said control and second electrodes are connected in circuit with at least one of said motor and exciter rotating windings whereby energy flowing from the motor rotating winding to the exciter rotating winding during said one half-cycle back biases said control and second electrode to render said semiconductor switching device nonconductive during said startup mode.

Claim 9

The control circuit of claim 7 wherein energy flowing from the motor rotating winding to the exciter rotating winding during said opposite half-cycle back biases said first and second electrodes to render said semiconductor switching device nonconductive during said startup mode.

Claim 10

The control circuit of claim 8 wherein said first and second electrodes and said control and second electrodes of said semiconductor switching device are forward biased when electrical energy is flowing from said exciter rotating winding to said motor rotating winding to render said semiconductive device conductive during the running mode.

Claim 11

In a synchronous motor unit having a stationary winding, a rotating winding, and an exciter unit having a rotating winding electrically connected to the motor rotating winding and a stationary winding, the motor unit being adapted to be operated in a startup mode wherein electrical energy is fed from the motor rotating winding to the exciter rotating winding and a running mode wherein electrical energy is fed from the exciter rotating winding to the motor rotating winding, a synchronizer control circuit coupled to the motor rotating winding for controlling the application of electrical energy from the exciter unit to the motor unit during the startup mode, the motor unit generAting a signal wave during the startup mode having a first characteristic which varies as a function of the slip frequency of the motor unit during the startup mode and a second characteristic, a slip frequency sensing circuit mounted stationary relative to the motor unit stationary winding comprising an impedance element electrically connected in circuit with the exciter stationary winding, means for preselecting a reference slip frequency, said slip frequency sensing circuit generating a control signal when said sensed slip frequency bears a preselected relationship to said preselected slip frequency and switching means for applying exciter energy to the motor unit in response to said control signal and said second characteristics, said signal wave being sensed in said slip frequency sensing circuit across said impedance element.

Claim 12

In a synchronous motor unit having a stationary winding, a rotating winding, and an exciter unit having a rotating winding electrically connected to the motor rotating winding and a stationary winding, the motor unit being adapted to be operated in a startup mode wherein electrical energy is fed from the motor rotating winding to the exciter rotating winding and a running mode wherein electrical energy is fed from the exciter rotating winding to the motor rotating winding, a synchronizer control circuit coupled to the motor rotating winding for controlling the application of electrical energy from the exciter unit to the motor unit during the startup mode, the motor unit generAting a signal wave during the startup mode having a first characteristic which varies as a function of the slip frequency of the motor unit during the startup mode and a second characteristic, a slip frequency sensing circuit mounted stationary relative to the motor unit stationary winding comprising an impedance element electrically connected in circuit with the exciter stationary winding, means for preselecting a reference slip frequency, said slip frequency sensing circuit generating a control signal when said sensed slip frequency bears a preselected relationship to said preselected slip frequency and switching means for applying exciter energy to the motor unit in response to said control signal and said second characteristics, said signal wave being sensed in said slip frequency sensing circuit across said impedance element.

Claim 13

The synchronizer control circuit of claim 10 wherein said first characteristic includes a signal of substantially constant amplitude having a duration related to the period of the slip frequency and said second characteristic includes at least one pulse differing in amplitude from said first characteristic.

Claim 14

The synchronizer control circuit of claim 11 wherein said switching means includes a first and second switching device connected to respond to said first and second characteristic, respectively, so that said energy flows from the exciter to the field in response to the conduction through both said first and second switching devices.

Claim 15

The synchronizer control circuit of claim 11 wherein said switching means includes a relay circuit connected in controlling relation with the exciter energy supply, a first switch being connected to respond to said second characteristic and second switch being connected to respond to said first characteristic, said switches being connected in series with said relay circuit, said relay circuit being enabled in response to the conduction of energy through both said first and second switches.

Claim 16

The synchronizer control circuit of claim 13 wherein said first and second switches are semiconductor devices having first and second electrodes connected in series with said relay circuit, and control electrodes for controlling the flow of current through said semiconductor devices.

Claim 17

The synchronizer control circuit of claim 14 wherein said slip frequency sensing circuit is connected to the control electrode of said second semiconductor device to cause conduction of said semiconductor device when said sensed slip frequency exceeds said preselected slip frequency.

Claim 18

The synchronizer control circuit of claim 15 further including a detection circuit for detecting said at least one pulse and wherein said first semiconductor device control electrode is connected directly to said detector circuit to cause conduction of said first semiconductor device in response to said at least one pulse.

Claim 19

The synchronizer control circuit of claim 10 wherein said first characteristic has a duration related to the period of the slip frequency and said frequency sensing circuit includes timing circuit means for timing the duration of said first characteristic.

Claim 20

The synchronizer control circuit of claim 17 wherein said timing circuit is reset in response to said second characteristic and is timed out to produce said control signal when said sensed slip frequency exceeds said preselected slip frequency.

Claim 21

The synchronizer control circuit of claim 15 wherein said first characteristic has a duration related to the period of the slip frequency and said frequency sensing circuit includes timing circuit means for timing the duration of said first characteristic.

Claim 22

The synchronizer control circuit of claim 19 wherein said timing circuit is reset in response to said second characteristic and is timed out to produce said control signal when said sensed slip frequency exceeds said preselected slip frequency.

Claim 23

The synchronizer control circuit of claim 13 wherein the motor unit synchronizes prior to the appLication of the exciter energy to the motor unit and fails to generate said second characteristic, said synchronizer control circuit further including a synchronizer override circuit connected to said first switch for providing an enabling signal to permit energy to flow through said first switch, in the absence of said second characteristic.

Claim 24

The synchronizer control circuit of claim 21 wherein said first characteristic has a duration related to the period of the slip frequency and said frequency sensing circuit includes timing circuit means for timing the duration of said first characteristic.

Claim 25

The synchronizer control circuit of claim 22 wherein said timing circuit is reset in response to said second characteristic and is timed out to produce said control signal when said sensed slip frequency exceeds said preselected slip frequency.

Claim 26

The synchronizer control circuit of claim 23 wherein said override circuit includes a timing circuit which times out after a preselected period has lapsed and is reset in response to said second characteristic, said preselected period being greater in duration than the time out duration of the slip frequency sensing circuit timing circuit.

Claim 27

In a synchronous motor unit having a stationary winding, a rotating winding, and an exciter unit having a rotating winding electrically connected to the motor rotating winding, a stationary winding and a selectably connectable source of electrical energy, including a switching circuit for connecting the source to the exciter stationary winding, the motor unit being adapted to be operated in a running mode wherein electrical energy is fed from the exciter rotating winding to the motor rotating winding, and an abnormal mode wherein a fault signal is fed, in a direction, through the exciter airgap from the exciter unit rotating winding to the exciter unit stationary winding, a sensing circuit for sensing the fault signal and disconnecting the source form the exciter comprising a sensing circuit for sensing the fault signal and an enabling circuit for enabling the sensing circuit in response to the energization of the switching circuit.

Claim 28

In a synchronous motor unit having a stationary winding, a rotating winding, and an exciter unit having a rotating winding electrically connected to the motor rotating winding, a stationary winding and a selectably connectable source of electrical energy, including a switching circuit for connecting the source to the exciter stationary winding, the motor unit being adapted to be operated in a running mode wherein electrical energy is fed from the exciter rotating winding to the motor rotating winding, and an abnormal mode wherein a fault signal is fed, in a direction, through the exciter airgap from the exciter unit rotating winding to the exciter unit stationary winding, a sensing circuit for sensing the fault signal and disconnecting the source form the exciter comprising a sensing circuit for sensing the fault signal and an enabling circuit for enabling the sensing circuit in response to the energization of the switching circuit.

Claim 29

The sensing circuit of claim 25 wherein said sensing circuit and said enabling circuit are connected in an AND logic configuration, said sensing circuit being connected in controlling relation to the switching circuit to disconnect the energy source.

Claim 30

The sensing circuit of claim 26 wherein said enabling circuit includes a timing circuit having a predetermined time-out period, said period being started in response to the actuation of the switching circuit.

Claim 31

The sensing circuit of claim 27 further including a semiconductor device connected to disable the switching circuit in one conductive state of the semiconductor device and enable the switching circuit in another conductive state of the semiconductor device, said sensing circuit being connected to control the conduction of the semiconductor device.

Claim 32

The sensing circuit of claim 28 wherein the said enabling circuit includes a switch connected in circuit with said timing circuit, said switch resetting the said timing circuit and holding the said timing circuit reset when the switching circuit is disabled, said sensing circuit including a semiconductor device having a first and second main current carrying electrode, and said enabling circuit having a first and second main current carrying electrode, said electrodes being connected in series circuit to provide a low impedance current path for electrical energy flowing from said timing circuit.