Reluctance type electric motor

• US 5,111,091 A
• Filed: 05/01/1991
• Issued: 05/05/1992
• Est. Priority Date: 09/08/1989
• Status: Expired due to Fees

• Current Assignee: Kabushikigaisha Sekogiken
• Original Assignee: Kabushikigaisha Sekogiken
• Inventors: Bahn, Itsuki
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): LABALLE, CLAYTON E
• Application Number:
  US07/689,051
• Time in Patent Office: 370 Days
• Field of Search: 310/68 R, 310/68 B, 310/77, 310/166, 318/138, 318/254, 318/368, 318/373, 318/375, 318/376, 318/381, 318/439
• US Class Current: 310/68.00B
• CPC Class Codes: H02P 25/089 Sensorless control direct torque control H02P23/30
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position

Abstract

A reluctance type electric motor, when an energization current in an exciting coil is interrupted at the end of a position detection signal, large magnetic energy stored in the exciting coil is prevented from being fed back to a power source by a reverse current prevention diode (43a, 43b) and it is forcedly caused to flow into an exciting coil to be next energized. Extinction of the stored magnetic energy in the preceding-stage exciting coil and accumulation of magnetic energy in the succeeding-stage exciting coil can be rapidly effected. A high-speed rotation (up to approximately 100,000 r.p.m.) can be attained with high torque obtained. If a plurality of teeth usually used for magnetic poles are provided, an effect that output torque increased by several times can be attached when a normal rotation speed is obtained. Since a chopper circuit is operated when the rotating operation is set to a reverse rotation mode, a voltage applied to the exciting coil becomes equal to the sum of a DC power source voltage and a counter-electromotive force so as to rapidly raise the exciting current, and when it reaches a preset current, energization is interrupted to make the fall of the magnetic energy stored in the exciting coil dull, and in this period of time, electric power is caused to flow into the power source by a transistor connected in parallel with the reverse current prevention diode (43a, 43b) and thus regenerated.

Claims

1. A two-phase reluctance type electric motor capable of effecting regenerative braking including a DC power source having a positive side and a negative side, comprising:

a position detecting device for detecting positions of salient poles of a rotor by use of a plurality of position detection elements fixed on a fixed armature side with a preset separation angle and deriving an electrical signal having first, second, third and fourth position detection signals of a width of 90 electrical degrees which are cyclically generated to continue to one another without being superposed on one another;

a plurality of first and second exciting coils each having first and second ends;

first semiconductor switching elements series-connected to the first and second ends of said first and second exciting coils, said plurality of first exciting coils and said plurality of second exciting coils respectively forming first- and second-phase exciting coils;

first diodes connected in a reverse direction to the series-connected bodies of said first semiconductor switching elements and said exciting coils;

an energization control circuit for energizing said first semiconductor switching elements series-connected to both ends of said first and second exciting coils according to the first, second, third and fourth position detection signals to energize said exciting coils by means of a DC power source so as to rotate the motor in a forward direction or energizing said first semiconductor switching elements series-connected to said first and second exciting coils according to the position detection signals which cause reverse-rotation torque to energize said exciting coils by means of said DC power source so as to rotate the motor in a reverse direction;

a detection circuit for deriving detection signals proportional to exciting currents flowing in said exciting coils;

first and second chopper circuits for holding said exciting currents to preset values according to the detection signal outputs of said detection circuit;

a second diode for reverse current prevention connected to the DC power source;

a second semiconductor switching element for short-circuiting connected in parallel with said second diode, the current conducting direction being set to an opposite direction;

an electric circuit for holding said second semiconductor switching element for short-circuiting in an OFF state for a first period of time corresponding to a short time length of an electrical signal obtained at an end of the first, second, third and fourth position detection signals and holding said second semiconductor switching element in an ON state during a second period of time in response to the electrical signal;

an electric circuit for preventing magnetic energy stored in one of said exciting coils when energization of a corresponding one of said exciting coils is interrupted at the end of a corresponding one of the position detection signals is fed back to the DC power source via said second diode of reverse current prevention connected switching element for short-circuiting, causing the stored magnetic energy to flow into the exciting coils to be energized by a next one of the position detection signals to rapidly extinguish the same and eliminating counter torque and reduced torque which are respectively generated by energization caused by discharge of the magnetic energy and energization caused from a starting portion of the position detection signal until the exciting current rises to a preset value;

an electric circuit for making the rise of current during the energization by said chopper circuit steeper by adding together the electromotive force caused by reduction in the amount of flux crossing the exciting coils and the DC power source voltage when a rotating operation is changed to a reverse rotation mode during the forward rotating direction and making the fall of the DC power source voltage dull to effect electromagnetic braking by supplying current to the positive side of the DC power source via said second semiconductor switching element for short-circuiting by a voltage obtained by adding together the electromagnetic force caused by reduction in the amount of flux crossing the exciting coils in the falling portion of current and the electromagnetic force caused by discharge of magnetic energy stored in the exciting coils so as to regenerate electric power; and

means for adjusting and fixing the positions of said position detection elements so that energization of said exciting coils can be effected to make the output torque of said exciting coils maximum.

2. A three-phase reluctance type electric motor capable of effecting regenerative braking including a DC power source, comprising:

a position detecting device having three position detection elements disposed separately from one another by 120 electrical degrees, for detecting the positions of salient poles of a rotor to derive an A-phase position detection signal having first, second and third position detection signals which each have a width of 120 electrical degrees and are cyclically generated to continue to one another without being superposed on one another and fourth, fifth and sixth position detection signals of B phase of the same construction which have a phase difference of 60 electrical degrees with respect to the A-phase position detection signal and are cyclically generated;

a plurality of exciting coils each having first and second ends;

first semiconductor switching elements series-connected to the first and second ends of A- and B-phase exciting coils, a first-phase exciting coil is constructed by a plurality of first exciting coils, a second-phase exciting coil is constructed by a plurality of second exciting coils, a third-phase exciting coil is constructed by a plurality of third exciting coils, first ones of said first, second and third exciting coils are combined to form said A-phase exciting coil, and second ones of said first, second and third exciting coils are combined to form said B-phase exciting coil;

first diodes connected in a reverse direction to the series-connected bodies of said first semiconductor switching elements and said exciting coils;

a first energization control circuit for energization control of said A-phase exciting coil and a second energization control circuit for energization control of said B-phase exciting coil, for cyclically energizing said first semiconductor switching elements series-connected to both ends of said A-phase exciting coil in response to the A-phase position detection signal to supply current to a corresponding one of said exciting coils from a DC power source, and cyclically energizing said first semiconductor switching elements series-connected to both ends of said B-phase exciting coil in response to the B-phase position detection signal to supply current to a corresponding one of said exciting coils from the DC power source so as to rotate the motor in a forward direction, or cyclically energizing said first semiconductor switching elements series-connected to both ends of said B-phase exciting coil in response to the A-phase position detection signal to supply current to a corresponding one of said exciting coils from the DC power source, and cyclically energizing said first semiconductor switching elements series-connected to both ends of said B-phase exciting coil in response to the A-phase position detection signal to supply current to a corresponding one of said exciting coils from the DC power source so as to rotate the motor in a reverse direction;

first and second detection circuits for deriving first and second detection signals proportional to exciting currents flowing in said A-phase and B-phase exciting coils;

first and second chopper circuits for holding the exciting currents in said A-phase and B-phase exciting coils at preset values;

second and third diodes for reverse current prevention connected to the DC power source for supplying current to said first and second energization control circuits;

second and third semiconductor switching elements for short-circuiting respectively connected in parallel with said second and third diodes and having current conducting directions set in the opposite directions to each other;

an electric circuit for holding said second and third semiconductor switching elements for short-circuiting in an OFF state for a first period of time corresponding to a short time length of an electrical signal obtained at an end of the A-phase and B-phase position detection signals and holding them in an ON state during a second period of time;

an electric circuit for preventing magnetic energy stored in one of said exciting coils when energization of a corresponding one of said exciting coils is interrupted at the end of a corresponding one of the A-phase and B-phase position detection signals is fed back to the DC power source via said second or third diode of reverse current prevention connected in parallel with said second or third semiconductor switching element for short-circuiting, causing the stored magnetic energy to flow into a next one of said exciting coils to be energized by a next one of the position detection signals to rapidly extinguish the same and eliminating counter torque and reduced torque which are respectively generated by energization caused by discharge of the magnetic energy and energization caused from a starting portion of the position detection signal until the exciting current rises to a preset value;

an electric circuit for making the rise of current during the energization by the chopper circuit steeper by adding together the electromotive force caused by reduction in the amount of magnetic flux crossing said exciting coils and the DC power source voltage when a rotating operation is changed to a reverse rotation mode in the forward rotating direction and making the fall of the DC power source voltage dull to effect electromagnetic braking by supplying current to the positive side of the DC power source via said second or third semiconductor switching element for short-circuiting by a voltage obtained by adding together the electromagnetic force caused by reduction in the amount of magnetic flux crossing said exciting coils in the falling portion of current and the electromagnetic force caused by discharge of magnetic energy stored in said exciting coils so as to regenerate electric power; and

means for adjusting and fixing the positions of said position detection elements so that energization of said exciting coils can be effected to make the output torque of said exciting coils maximum.

3. A three-phase half-wave reluctance type electric motor capable of effecting regenerative braking, comprising:

a position detecting device including three position detection elements for deriving a position detection signal having first, second and third position detection signals which each have a width of 120 electrical degrees and are cyclically generated to continue to one another without being superposed on one another so as to detect the position of a rotor;

first-, second- and third-phase exciting coils having first and second ends wound on first-, second- and third-phase magnetic poles;

first semiconductor switching elements series-connected to the first and second ends of said first-, second- and third-phase exciting coils;

first diodes connected in a reverse direction to series-connected bodies of said first semiconductor switching elements and said exciting coils;

an energization control circuit for cyclically energizing said first semiconductor switching elements series-connected to both ends of said first, second and third exciting coils according to the first, second and third position detection signals to energize a corresponding one of said exciting coils by means of a DC power source so as to rotate the motor in a forward direction, or cyclically energizing said first semiconductor switching elements series-connected to said first and second exciting coils according to the three-phase position detection signals which cause reverse-rotation torque to energize said exciting coils by means of the DC power source so as to rotate the motor in a reverse direction;

a detection circuit for deriving detection signals proportional to exciting currents flowing in said exciting coils;

first and second chopper circuits for holding the exciting currents to preset values according to the detection signal outputs of said detection circuit;

a second diode for reverse current prevention connected to the DC power source for supplying current to said energization control circuit;

a second semiconductor switching element for short-circuiting connected in parallel with said second diode for reverse current prevention, the current conducting direction thereof being set in an opposite direction;

an electric circuit for holding said second semiconductor switching element for short-circuiting in an OFF state for a first period of time corresponding to a short time length of an electrical signal obtained at an end of the three-phase position detection signals and holding said second semiconductor switching element in an ON state during a second period of time in response to the electrical signal;

an electric circuit for preventing magnetic energy stored in one of said exciting coils when energization of a corresponding one of said exciting coils is interrupted at the end of a corresponding one of the three-phase position detection signals is fed back to the DC power source via said second diode of reverse current prevention connected in parallel with said second semiconductor switching element for short-circuiting, causing the stored magnetic energy to flow into the exciting coils to be energized by a next one of the position detection signals to rapidly extinguish the same and eliminating counter torque and reduced torque which are respectively generated by energization caused by discharge of the magnetic energy and energization caused from a starting portion of the position detection signal until the exciting current rises to a preset value;

an electric circuit for making the rise of current during the energization by said chopper circuit steeper by adding together the electromotive force caused by reduction in the amount of magnetic flux crossing said exciting coils and the DC power source voltage when a rotating operation is changed to a reverse rotation mode in the forward rotating direction and making the fall of the current dull to effect electromagnetic braking by supplying current to the positive side of the DC power source via said second semiconductor switching element for short-circuiting by a voltage obtained by adding together the electromagnetic force caused by reduction in the amount of magnetic flux crossing said exciting coils in the falling portion of current and the electromagnetic force caused by discharge of magnetic energy stored in said exciting coils so as to regenerate electric power; and

means for adjusting and fixing the positions of said position detection elements so that energization of said exciting coils can be effected to make the output torque of the exciting coils maximum.