Commutated motor including commutation means responsive to reactive voltage induced in armature windings

Claim 2

In an electronically commutated motor having three phase windings, a commutating and control circuit comprising direct current supply means, commutating switching means for selectively connecting said phase windings with said supply means to energize said windings, control circuit means for controlling said commutating switching means, said control circuit means comprising means for generating control pulses at a selected frequency and means controlled by said pulses for controlling commutating switching means to render said switching means selectively and sequentially conductive to energize the respective phase windings cyclically at a selected rate, means for sensing reactive voltage induced in each of said phase windings and blocking means connected with and controlled by said sensing means in response to excessive induced voltage in a nonselected non-energizing winding for actuating said control circuit means to render the respective switching means of the selected energized phase winding non-conductive and thereby avoid excessive short circuit current being produced in said windings by said induced voltage, said sensing means comprising a transformer having a primary in which a voltage is induced by the presence of an excessive reactive voltage in said non-selected winding and a secondary connected with and applying a voltage to said blocking means on the occurrence of said excessive voltage.

Claim 3

A motor according to claim 1, wherein said transformer is a three phase transformer having primary windings inductively coupled with respective ones of said phase windings for developing induced voltages therein proportional to voltages induced in said phase windings.

Claim 4

A motor according to claim 2, wherein said blocking means comprises a blocking switching means overriding the control of said commutating switching means by said control circuit means to render said commutating switching means non-conductive in the event of excessive induced voltage in a non-selected phase winding, said blocking switching means being coupled with and controlled by said secondary windings of said transformer.

Claim 5

A motor according to claim 1, further including protective means for preventing the premature opening of the commutating switching means of non-selected phase windings during operation of said blocking means.

Claim 6

A motor according to claim 4, wherein said commutating switching means comprises power switching means, control switching means and control transformer means having primaries coupled with said control switching means and secondaries controlling said power switching means, said protective means comprising means for dissipating any excessive voltage induced in said control transformer when all Of said control switching means are simultaneously non-conductive.

Claim 7

In an electronically commutated motor having a plurality of phase windings, a commutating and control circuit comprising direct current supply means having positive and negative poles, commutating switching means comprising individual switching means for connecting each said phase winding with said supply means to energize the respective winding, control circuit means controlling said commutating switching means to render said switching means selectively and sequentially conductive to energize the respective phase winding cyclically at a selected rate, said control circuit means comprising means for generating control pulses at a selected frequency and means controlled by said pulses for controlling commutating switching means and circuit protecting means comprising blocking means, means for measuring short circuit current occurring in said motor windings by reason of voltage induced in said windings, and means responsive to excessive short circuit current for actuating said blocking means to interrupt said excessive short circuit current, said means for measuring the short circuit current comprises a resistance divided into two parts, one part thereof being traversed by a commutation current and the other part thereof being traversed by an induced current, said two currents occurring simultaneously during the short circuiting of the voltage induced in the windings of said motor and means responsive to the voltage drops across said resistance parts.

Claim 8

In an electronically commutated motor having a plurality of phase windings, a commutating and control circuit comprising direct current supply means having positive and negative poles, commutating switching means comprising individual switching means for connecting each said phase winding with said supply means to energize the respective winding, control circuit means controlling said commutating switching means to render said switching means selectively and sequentially conductive to energize the respective phase winding cyclically at a selected rate, said control circuit means comprising means for generating control pulses at a selected frequency and means controlled by said pulses for controlling commutating switching means and circuit protecting means comprising blocking means, means for measuring short circuit current occurring in said motor windings by reason of voltage induced in said windings, and means responsive to excessive short circuit current for actuating said blocking means to interrupt said excessive short circuit current, said means for measuring the short circuit current comprises a resistance divided into two parts, one part thereof being traversed by a commutation current and the other part thereof being traversed by an induced current, said two currents occurring simultaneously during the short circuiting of the voltage induced in the windings of said motor and means responsive to the voltage drops across said resistance parts.

Claim 9

A motor according to claim 6, wherein said circuit protecting means includes a transformer having a primary and a secondary, said primary and a high frequency chopper being connected in series across said resistance and said secondary controlling said blocking means.

Claim 10

A motor according to claim 6, wherein said circuit protecting means comprises two like parts, one controlling those individual switching means for connecting said phase windings with said positive pole and the other controlling those individual switching means for connecting said phase windings with said negative pole.

Claim 11

A motor according to claim 6, wherein said blocking means comprises a bistable circuit which is activated to blocking condition by said excessive short circuit current and is reset to non-blocking condition by each recurring said pulse.

Claim 12

In an electronically commutated motor having a plurality of phase windings, a commutating and control circuit comprising direct current supply means having positive and negative poles, commutating switching means comprising individual switching means for connecting each said phase winding selectively with said positive and negative poles to energize said windings, said switching means being controllable by application of electrical pulses thereto, control circuit means for controlling said commutating switching means to render said switching means selectively and sequentially conductive to energize respective phase windings cyclically at a selected rate, said control circuit means including pulse generating means for generating pulses at a selected rate and means for distributing said pulses cyclically to said commutating switching means to control said commutating switching means, and circuit protecting means comprising means for sensing short circuit current occurring in said phase windings by reason of reactive voltage induced in said windings, and blocking means responsive to excessive induced short circuit current in said phase windings for blocking said commutating switching means to render said commutating switching means non-conductive and thereby open the circuit of said short circuit current, said sensing means comprising a transformer having a primary in which a voltage is produced by excessive short circuit current in said phase windings and a secondary connected with and applying a voltage to said blocking means on the occurrence of such excessive short circuit current.

Claim 13

In an electronically commutated motor having a plurality of phase windings, a commutating and control circuit comprising direct current supply means having positive and negative poles, commutating switching means comprising individual switching means for connecting each said phase winding selectively with said positive and negative poles to energize said windings, said switching means being controllable by application of electrical pulses thereto, control circuit means for controlling said commutating switching means to render said switching means selectively and sequentially conductive to energize respective phase windings cyclically at a selected rate, said control circuit means including pulse generating means for generating pulses at a selected rate and means for distributing said pulses cyclically to said commutating switching means to control said commutating switching means, and circuit protecting means comprising means for sensing short circuit current occurring in said phase windings by reason of reactive voltage induced in said windings, and blocking means responsive to excessive induced short circuit current in said phase windings for blocking said commutating switching means to render said commutating switching means non-conductive and thereby open the circuit of said short circuit current, said sensing means comprising a transformer having a primary in which a voltage is produced by excessive short circuit current in said phase windings and a secondary connected with and applying a voltage to said blocking means on the occurrence of such excessive short circuit current.

Claim 14

A motor according to claim 10, comprising means for preventing premature opening of the commutating switching means of non-selected phase windings in the event of operation of said blocking means.

Claim 15

A motor according to claim 11, in which said commutating switching means comprises commutating transistors, control transistors and transformer means coupling said commutating transistors with said control transistors so that the conduction of said commutating transistors is controlled by the conduction of corresponding said control transistors, and in which said means for preventing premature opening of the commutating switching means of non-selected phase windings comprises means for dissipating excess voltage induced in said transformer means opon operation of said blocking means.