Reluctance-type motor and a DC motor capable of performing regenerative braking

• US 5,432,420 A
• Filed: 02/15/1994
• Issued: 07/11/1995
• Est. Priority Date: 06/29/1992
• Status: Expired due to Term

• Current Assignee: Lloyd & Associates
• Original Assignee: Kabushikigaisha Sekogiken
• Inventors: Bahn, Itsuki
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US08/196,261
• Time in Patent Office: 511 Days
• Field of Search: 318/701, 318/138, 318/254, 318/685, 318/696, 318/375, 318/376, 310/68 B, 310/106
• US Class Current: 318/701
• CPC Class Codes: H02P 25/089 Sensorless control direct torque control H02P23/30
• CPC Class Codes: H02P 3/065 for stopping or slowing a reluctance motor

Abstract

A reluctance type motor and a brushless DC motor having large torque and good efficiency in a high-speed region.

When one exciting coil or armature coil is deactivated, magnetic energy stored in the magnetic core is prevented from returning to the electric power source side by means of a back-flow preventing diode. The magnetic energy is charged in a small-capacitance capacitor so as to hold it at a high voltage, thereby causing exciting current to decrease steeply. After a predetermined time has elapsed, a next exciting or armature coil is activated. In this case, the high voltage charged in the capacitor is applied, so that the exciting current builds up sharply. Since the building-up and the trailing-off of the exciting current of the exciting coil can be made sharp, not only the rotational speed can be increased up to several 10 thousands rpm but regenerative braking can be made available by switching the motor rotating in the normal mode into the reverse rotation mode so as to generate adequate reverse torque through the chopper circuit.

Claims

1. A plural-phase reluctance type motor with a fixed armature and a magnetic rotor comprising:

a plurality of salient poles of equal width disposed on an outer surface of said magnetic rotor at regular intervals of equal angle;

2n pieces (n;

a positive integer not less than

     3) of magnetic poles protruding from an inner peripheral surface of said fixed armature, symmetrically disposed magnetic poles being in-phase, said magnetic poles confronting said salient poles over slight gap, being disposed at regular intervals and having a 120- through 180-degree circumferential width in terms of electric angle to be wound with an exciting coil;

plural-phase exciting coils wound around said magnetic poles;

a position detecting device for detecting rotational positions of said salient poles and generating plural-phase position detecting signals;

a first switching element installed at one end of each exciting coil;

a DC electric power source supplying electric power to a serial joint unit consisting of said first switching element and said each exciting coil;

a current supply control circuit for obtaining output torque by supplying current to said plural-phase exciting coils by turning on corresponding first switching elements connected to said exciting coils in response to said plural-phase position detecting signals by the duration of signal of each position detecting signal;

a first electric circuit for transferring magnetic energy stored in the exciting coil through a diode into a small-capacitance capacitor for storage from a negative terminal of the exciting coil to quickly reduce exciting current of said exciting coil, when said first switching element is turned off at a terminal end of said position detecting signal;

a second electric circuit for discharging electrostatic energy stored in said small-capacitance capacitor into said exciting coil through a semiconductor switching element activated together with said first switching element from a positive terminal of said exciting coil, to quickly build up exciting current, when said exciting coil is activated by said first switching element in response to said position detecting signal after said magnetic rotor rotates a predetermined angle;

a switching device for switching the motor between normal and reverse rotations by turning on said first switching element in response to said plural-phase position detecting signal;

a detecting circuit for generating a detection electric signal when exciting current of said exciting coil exceeds a predetermined value;

a chopper circuit for turning off said first switching element connected to said exciting coil in response to said detection electric signal and turning on this first switching element after a predetermined time to maintain exciting current at a predetermined value;

an electric closed circuit comprising the negative terminal of said exciting coil, said diode, second switching element, positive terminal of the electric power source, negative terminal of the electric power source, diode inversely connected to said exciting coil, and the positive terminal of said exciting coil;

a third electric circuit for, activating said second switching element by the same interval as that of the exciting coil of each phase; and

a fourth electric circuit for, when the motor rotating in the normal direction is switched to a reverse rotation mode, quickly building up chopper-controlled current by applying a sum of the voltage of the DC electric power source and an electromotive force due to reduction of magnetic flux intersecting the exciting coil, and further, in trailing-off section, supplying to the positive terminal of the DC electric power source through said second switching element with current corresponding to the sum of the electromotive force due to reduction of magnetic flux intersecting the exciting coil and the electromotive force due to discharge of magnetic energy stored by said exciting coil, thereby regenerating the electric power and making gentle the slope of said trailing-off section of the current so as to perform braking.

2. A three-phase half-wave current supply mode reluctance type motor, comprising:

a plurality of salient poles of equal width disposed on an outer surface of a magnetic rotor at regular intervals of the same angle;

6n (n;

a positive integer) pieces of magnetic poles protruding from an inner peripheral surface of a fixed armature, symmetrically disposed magnetic poles being in-phase, said magnetic poles confronting said salient poles over slight gap, being disposed at regular intervals and having a 120- or 180-degree circumferential width in terms of electric angle to be wound with an exciting coil;

said No.1-, No.2- and No.3-phase exciting coils wound around said magnetic poles;

a position detecting device including a plurality of position detecting elements for detecting rotational positions of said salient poles and generating No.1-phase position detecting signals of rectangular waveform having the same width of 120-degree electric angle and a phase difference of 360-degree electric angle therebetween, and No.2- and No.3-phase position detecting signals of rectangular waveform having the same width and phase difference as the No.1-phase position detecting signals but being successively delayed one another from the No.1-phase position detecting signals by 120-degree electric angle;

a switching element connected to both ends of each exciting coil;

a diode inversely connected to each serial joint unit of said switching element and corresponding exciting coil;

first, second and third current supply control circuits for turning on said switching elements connected to both ends of the exciting coils in response to said No.1-, No.2- and No.3-phase position detecting signals to supply current to said No.1-, No.2- and No.3-phase exciting coils through first, second and third back-flow preventing diodes, respectively connected to the DC electric power source in a forward direction for rotating the motor in the normal direction, or turning on said switching elements connected to both ends of said exciting coils in response to said No.1-, No.2- and No.3-phase position detecting signals for generating reverse rotation torque to supply current to said No.1-, No.2- and No.3-phase exciting coils for rotating the motor in a reverse direction;

first, second and third capacitors of small capacitances for storing magnetic energies discharged from said No.1-, No.2- and No.3-phase exciting coils through said diodes with one end connected to the negative voltage side of said exciting coil, respectively, so as to quickly reduce exciting current when said No.1-, No.2- and No.3-phase exciting coils are deactivated at the terminal ends of said position detecting signals;

a first electric circuit for supplying high-voltage electrostatic energy charged in the first, second and third capacitors to the next activated exciting coils together with the voltage of said DC electric power source, so as to make exciting current build up quickly;

a chopper circuit for deactivating said exciting coil when its exciting current exceeds a predetermined value and activating said exciting coil when the exciting current decreases to a predetermined value;

first, second and third semiconductor switching elements connected in parallel with current supply circuits of said first, second and third diodes so that respective current supply directions become opposite to those of said current supply control circuits;

a second electric circuit for activating said first, second and third semiconductor switching elements for duration of said No.1-, No.2- and No.3-phase position detecting signals, respectively;

a third electric circuit for quickly building up chopper-controlled current by applying a sum of the voltage of the DC electric power source and an electromotive force due to reduction of magnetic flux intersecting the exciting coil, and further for slowly decreasing the current by performing regenerative braking so as to regenerate the electric power through said first, second and third semiconductor switching elements to the positive terminal of the DC electric power source by applying a voltage as a sum of the electromotive force due to reduction of magnetic flux intersecting the exciting coil and an electromotive force due to discharge of magnetic energy stored in said exciting coil, when the motor rotating in the normal direction is switched to a reverse rotation mode; and

a means for fixing said position detecting elements on the fixed armature side so that said exciting coils wound around said magnetic poles can be activated at a predetermined angle within an electric angle of approximately 30 degrees after said salient poles begin confronting with said magnetic poles.

3. A DC motor in a three-phase full-wave current supply mode reluctance type motor, comprising:

a plurality of salient poles of equal width disposed on an outer surface of a magnetic rotor at regular intervals of the equal angle;

12n (n;

a positive integer) pieces of magnetic poles protruding from an inner peripheral surface of a fixed armature, symmetrically disposed magnetic poles being in-phase, said magnetic poles confronting said salient poles over slight gap, being disposed at regular intervals and having a 120- or 180-degree circumferential width in terms of electric angle to be wound with an exciting coil;

No.1-, No.2- and No.3-phase exciting coils wound around said magnetic poles;

a position detecting device including a plurality of position detecting elements for detecting rotational positions of said salient poles and generating rectangular-waveform No.1-phase position detecting signals having the same width of 120-degree electric angle and a phase difference of 360-degree electric angle therebetween, and rectangular-waveform No.2- and No.3-phase position detecting signals having the same width and phase difference as the No.1-phase position detecting signals but being successively delayed one another from the No.1-phase position detecting signals by 120-degree electric angle, and further generating a rectangular-waveform No.1-phase position detecting signals having the same width and same phase difference as the No.1-phase position detecting signals but being delayed from said No.1-phase position detecting signals by 180-degree electric angle, and rectangular-waveform No.2- and No.3-phase position detecting signals having the same width and the phase difference as the No.1-phase position detecting signals but being successively delayed one another from the No.1-phase position detecting signals by 120-degree electric angle;

switching elements respectively connected to both ends of exciting coils, where a pair of said exciting coils of No.1-phase half-wave current mode are referred to as No.1- and No.1-exciting coils, and each pair of No.2-phase and No.3-phase half-wave current mode exciting coils are referred to as No.2- and No.2-exciting coils and No.3- and No.3-exciting coils respectively.

a diode inversely connected to a serial joint unit of said switching element and corresponding exciting coil;

a first electric circuit for turning on the switching elements connected to both ends of said No.1-, No.2- and No.3-exciting coils wound around said magnetic poles of the fixed armature for the duration of said No.1-, No.2- and No.3-phase position detecting signals and further turning on the switching elements connected with both ends of said No.1-, No.2- and No.3-exciting coils wound around other magnetic poles of the fixed armature for the duration of said No.1-, No.2- and No.3-phase position detecting signals so as to rotate the motor in a normal direction, or turning on the switching elements connected with both ends of said No.1-, No.2-, and No.3-exciting coils for the duration of said No.1-, No.2-, and No.3-phase position detecting signals and further turning on the switching elements connected with both ends of said No.1-, No.2- and No.3-exciting coils for the duration of said No.1-, No.2- and No.3-phase position detecting signals, so as to rotate the motor in the reverse direction;

first, second and third current supply control circuits for turning on said switching elements connected to both ends of the exciting coils so as to supply current to said No.1-, No.1-exciting coils, No.2-, No.2-exciting coils, and No.3-, No.3-exciting coils through first, second and third back-flow preventing diodes respectively connected to the DC electric power source in the normal direction;

first, second and third capacitors having small capacitances for storing magnetic energies discharged from said No.1-, No.1-exciting coils, No.2-, No.2-exciting coils, and No.3-, No.3-exciting coils through diodes having one end being connected to the negative voltage side of said exciting coil, respectively, so as to quickly reduce exciting current when said No.1-, No.1-exciting coils, No.2-, No.2-exciting coils, and No.3-, No.3-exciting coils are deactivated at the terminal ends of said position detecting signals;

a second electric circuit for supplying high-voltage electrostatic energy charged in the first second and third capacitors to the exciting coils to be next activated, together with the voltage of said DC electric power source, so as to make exciting current build up quickly;

a chopper circuit for deactivating each of said No.1-, No.1-, No.2, No.2-, No.3- and No.3-exciting coils when its exciting current has exceeded a predetermined value and activating said exciting coil when the exciting current decreases to a predetermined value;

first, second and third semiconductor switching elements connected in parallel with said first, second and third back-flow preventing diodes so that respective current supply directions become opposite to those of said current supply circuits;

a third electric circuit for activating said first, second, and third semiconductor switching elements for the duration of said No.1-, No.1-phase position detecting signals, No.2-, No.2-phase position detecting signals, and No.3-, No.3-phase position detecting signals, respectively;

a fourth electric circuit for quickly building up chopper-controlled current by applying a sum of the voltage of the DC electric power source and an electromotive force due to reduction of magnetic flux intersecting the exciting coil, as well as for slowly decreasing the current by regenerative braking so as to regenerate the electric power through said first, second and third semiconductor switching elements to the positive terminal of the DC electric power source by applying a voltage as a sum of the electromotive force due to reduction of magnetic flux intersecting the exciting coil and an electromotive force due to discharge of magnetic energy stored in said exciting coil, when the motor rotating in the normal direction is switched into a reverse rotation mode; and

a means for fixing said position detecting elements on the fixed armature side so that said exciting coils wound around said magnetic poles can be activated at a predetermined angle within an electric angle of approximately 30 degrees after said salient poles begin confronting with said magnetic poles.

4. A three-phase full-wave current supply mode DC motor including a fixed armature and a magnet rotor, comprising:

No.1-, No.2- and No.3-phase armature coils wound around magnetic poles of the fixed armature;

said armature coils including an armature coil being referred to as a No.1-phase armature coil in No.1-phase normal-direction current supply mode and referred to as a No.1-phase armature coil in No.1-phase reverse-direction current supply mode, armature coils being referred to as No.2- and No.3-phase armature coils in No.2-phase and No.3-phase normal-direction current supply modes and referred to as No.2- and No.3-phase armature coils in No.2-phase and No.3-phase reverse-direction current supply modes;

a position detecting device including a plurality of position detecting elements for detecting rotational positions of N- and S-poles of said magnet rotor and generating rectangular-waveform No.1-phase position detecting signals having the same width of 120-degree electric angle and a phase difference of 360-degree electric angle therebetween, rectangular-waveform No.2- and No.3-phase position detecting signals being successively delayed one another from the No.1-phase position detecting signals by 120-degree electric angle, rectangular-waveform No.1-phase position detecting signals having the same width and phase difference as the No.1-phase position detecting signals but being delayed from said No.1-phase position detecting signals by 120-degree electric angle, and rectangular-waveform No.2- and No.3-phase position detecting signals being successively delayed one another from the No.1-phase position detecting signals by 120-degree electric angle, where the armature coil is referred to as No.1-phase armature coil when in No.1-phase normal current supply mode and as No.1-phase armature coil when in No.1-phase reverse current supply mode, while the armature coil is referred to as No.2-phase and No.3-phase armature coils when in No.2- and No.3-phase normal current supply modes and as No.2- and No.3-phase armature coils when in No.2- and No.3-phase reverse current supply modes;

6 switching elements connected with both ends of each of said No.1-, No.1-, No.2-, No.2-, No.3-, No.3-armature coil;

diodes inversely connected to serial joint units each consisting of said switching element and its corresponding armature coil;

first, second and third current supply control circuits for turning on said switching elements connected to both ends of said No.1-, No.2-, No.3-, No.1-, No.2-and No.3-armature coils in response to corresponding No.1-, No.2-, No.3-, No.1-, No.2- and No.3-phase position detecting signals, so as to supply current through first, second, - - - sixth back-flow preventing diodes respectively connected to the DC electric power source in the forward direction for rotating the motor in a normal direction, or for turning on said switching elements connected to both ends of said No.1-, No.2-, No.3-, No.1-, No.2- and No.3-armature coils in response to No.1-, No.2-, No.3-, No.1-, No.2- and No.3-phase position detecting signals for generating reverse rotation torque so as to rotate the motor in a reverse direction;

first, second, - - - , sixth capacitors having small capacitances for storing magnetic energies discharged from said No.1-, No.2-, No.3-, No.1-, No.2- and No.3-armature coils through diodes having one end being connected to the negative voltage side of said armature coil, respectively, so as to quickly reduce armature current when said No.1-, No.2-, No.3-, No.1-, No.2-, and No.3-armature coils are deactivated at the terminal ends of said position detecting signals;

a first electric circuit for supplying high voltage electrostatic energy charged in the first, second, - - - , sixth capacitors to the next activated armature coils together with the voltage of said DC electric power source, so as to make armature current build up quickly;

a chopper circuit for deactivating each of said No.1-, No.2-, No.3-, No.1-, No.2- and No.3-armature coils when its armature current exceeds a predetermined value and activating said armature coil when the armature current decreases to a predetermined value;

first semiconductor switching element connected through a diode, from each of negative terminals of said No.1-, No.1-armature coils, to the positive terminal of the DC electric power source, and second and third semiconductor switching elements connected through a diode, from each of negative terminals of said No.2-, No.2-, No.3-, and No.3-armature coils, to the positive terminal of the DC electric power source;

a second electric circuit for activating said first, second, and third semiconductor switching elements for predetermined duration of said No.1-, No.1-phase position detecting signals, No.2-, No.2-phase position detecting signals, and No.3-, No.3-phase position detecting signals, respectively;

a third electric circuit for quickly building up chopper-controlled current by applying a voltage as a sun, of the voltage of the DC electric power source and an electromotive force due to reduction of magnetic flux intersecting the armature coil, and further for slowly decreasing the current by regenerative braking so as to recover the electric power through said first, second and third semiconductor switching elements to the positive terminal of the DC electric power source by applying a voltage as a sum of the electromotive force due to reduction of magnetic flux intersecting the armature coil and an electromotive force due to discharge of magnetic energy stored in said armature coil, when the motor rotating in the normal direction is switched into a reverse rotation mode; and

a means for fixing said position detecting elements on the fixed armature side so that maximum torque can be obtained when said armature coils are activated by 120-degree electric angle.