JPH09275698A - Drive circuit and control method for switched reluctance motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a simple drive circuit and a control method for switched reluctance motors with a short switching cycle. SOLUTION: Semiconductor switching elements 1, 2, 3, connected with the positive side of a direct-current power supply 11, are' series-connected with semiconductor switching elements 7, 8, 9, connected with the negative side, through armature coils 4, 5, 6 to form a first main circuit that on/off-controls the current of the armature coils. The armature coils 4, 5, 6 are placed between an auxiliary circuit formed by connecting a parallel circuit comprising a semiconductor switching element 23, a diode 14 and a reactor 13 to the positive side of the direct-current power supply 11, and the negative side of the direct-current power supply 11 through diodes 18, 19, 20, 15, 16, 17. In addition, a paralleled capacitor 10 is placed between the auxiliary circuit and the negative side of the direct-current power supply 11 to form a discharge circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable speed motor controlled by a drive circuit composed of switching elements used in electric vehicles, electric bicycles, cranes, etc.
The present invention relates to a drive circuit of an SR motor) and a control method thereof.

[0002]

2. Description of the Related Art A driving circuit for a conventional three-phase reluctance motor is shown in FIG. The drive circuit that supplies a current to the armature coil of each phase is configured by a series circuit including a diode, a semiconductor switching element, an armature coil, and a semiconductor switching element, and both ends of this series circuit are connected to the positive side of the DC power source. Each is connected to the minus side. Each drive circuit is on / off controlled according to a preset order, and current is sequentially supplied to the armature coils in each drive circuit to drive the reluctance motor.

In FIG. 10, taking a drive circuit including the armature coil 101 as an example, the semiconductor switching element 1
When 04 and 105 are turned on at the same time, "the positive side of the DC power supply-diode 110-semiconductor switching element 10
4 to armature coil 101 to semiconductor switching element 10
Current flows through the armature coil 101 via the loop circuit on the "5-negative side of the DC power supply". Next, when the two semiconductor switching elements 104 and 105 are turned off at the same time,
The inductive energy of the armature coil 101 charges the capacitor 119 via the loop circuit of "armature coil 101-diode 116-capacitor 119-diode 113-armature coil 101". Capacitor 119
The charging energy of the semiconductor switching elements 104 and 1
Emitted when 05 are turned on at the same time.

Although the above description relates to the operation of the drive circuit having the armature coil 101 as a constituent element, the drive circuit having the armature coils 102 and 103 as constituent elements can be similarly described, and the respective drive circuits are driven. Since the circuit is sequentially controlled to be turned on and off, the armature coil is also sequentially excited, and the rotor approaching the magnetized stator is attracted to the rotor one after another to continue the rotation of the rotor.

[0005]

As described above,
The circuit according to the prior art has a complicated discharge circuit for discharging the inductive energy of the armature coil during the off period of the semiconductor switching element, and is equivalent to three diodes, one expensive capacitor, and two capacitors. Need semiconductor switching elements. On the other hand, when the two semiconductor switching elements are turned off at the same time, the inductive energy of the armature coil is large. Therefore, in order to return this energy to the power source, it is necessary to lengthen the discharge time. Therefore,
The switching cycle cannot be shortened in order to complete the discharge while the semiconductor switching element is off, and thus it has been difficult to increase the rotation speed of the SR motor. The present invention has been made in order to solve the drawbacks of the drive circuit of the SR motor according to the prior art, and reduces the number of constituent parts of the drive circuit and reduces the armature coil when the semiconductor switching element is turned off. This is an improved discharge characteristic of induction energy.

[0006]

A drive circuit for a switched reluctance motor according to the present invention comprises two semiconductor switching elements, which are respectively connected to the positive side and the negative side of a DC power source, connected in series via an armature coil. The formed first main circuit is provided for each of the n armature coils, and the semiconductor switching element 23 and the diode 14 are provided.
And an auxiliary circuit formed by connecting the positive side of the DC power source through a parallel circuit composed of a reactor and a reactor 13 and two sets of semiconductor switching elements and electric machines in the n first main circuits, respectively. The discharge circuit is formed by connecting the connection points with the child coils via diodes, respectively, and further forming a parallel capacitor 10 connected between the auxiliary circuit and the negative side of the DC power supply.

The induction energy of the armature coil in the drive circuit of the switched reluctance motor described above is
The parallel capacitor 10 is charged through the two diodes connected to both ends of the armature coil, and when the charging voltage becomes higher than the DC power supply voltage and becomes equal to or higher than a preset voltage, semiconductor switching in the auxiliary circuit It is also possible to rapidly regenerate the inductive energy of the armature coil to the DC power supply via the DC-DC converter including the element 23, the parallel circuit of the diode 14 and the reactor 13, and the parallel capacitor 10.

In order to reduce the number of semiconductor switching elements in the first main circuit, a second main circuit in which the semiconductor switching elements in the first main circuit connected to the positive side of the DC power supply are omitted is formed, N second main circuits are connected in parallel to the semiconductor switching elements 21 connected in series on the positive side of the power source, and the semiconductor switching elements 21 are turned on in synchronization with the semiconductor switching elements in the n second main circuits. -A drive circuit for off control can also be configured.

[0009]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present invention, and shows a drive circuit of a switched reluctance motor having n armature coils. In addition, in order to simplify the description of the drawings, the drive circuit is provided with three armature coils. In FIG. 1, semiconductor switching elements 1, 2 and 3 having drain terminals respectively connected are connected to the positive side of the DC power supply 11, and the negative side of the DC power supply 11 is connected via the armature coils 4, 5 and 6. Are connected in series with the semiconductor switching elements 7, 8 and 9 whose source terminals are respectively connected to the armature coil 4,
A first main circuit having 5, 5 is formed.

According to a preset order, two sets of semiconductor switching elements in each of the n first main circuits are simultaneously turned on / off to sequentially supply currents to the armature coils in the first main circuit. Drive the switched reluctance motor.

When the above two sets of semiconductor switching elements are turned off at the same time, inductive energy is generated in the armature coil. A discharge circuit is provided to discharge this inductive energy during the off period. That is, the armature coils 4, 5, 6 and the semiconductor switching elements 7, 8, 9
The diodes 18, 19 and 2 provided at the respective connection points of
0 is connected to an auxiliary circuit formed by connecting to the positive side of the DC power supply 11 through a parallel circuit composed of the semiconductor switching element 23 and the diode 14 and the reactor 13, and the semiconductor switching elements 1, 2, 3 And the diode 15,1 provided at the connection point between the armature coil 4,5,6
6, 17 are connected to the negative side of the DC power supply 11,
Further, a parallel capacitor 10 is connected between the auxiliary circuit and the negative side of the DC power source 11 to form a discharge circuit.

Taking the case where the semiconductor switching elements 1 and 7 are simultaneously turned off as an example, the inductive energy of the armature coil 4 passes through the loop circuit of "diode 18-auxiliary circuit-parallel capacitor 10-diode 15". The parallel capacitor 10 is charged. When the charging voltage of the parallel capacitor 10 becomes higher than the DC power supply voltage, the parallel capacitor 10 is passed through the semiconductor switching element 23 in the auxiliary circuit, the parallel circuit including the diode 14 and the reactor 13, and the DC-DC converter including the parallel capacitor 10. The charging energy is regenerated by the DC power supply 11 via the diode 12. Therefore, the voltage of the parallel capacitor 10 is discharged before being charged by the inductive energy of the next armature coil. FIG. 2 is a waveform diagram showing the relationship between the switch timing of the semiconductor switching element and the change in the charging voltage of the parallel capacitor 10. The parallel capacitor 10 repeats charging and discharging in synchronization with the switching of the semiconductor switching element.

FIG. 3 is a block diagram showing the second embodiment, in which the semiconductor switching element 21 is connected in series to the positive side of the DC power supply 11 to connect the first main circuit in the first embodiment. The semiconductor switching element connected to the positive side of the DC power supply 11 to be formed is omitted. Therefore, the number of semiconductor switching elements and the number of diodes in the second embodiment may be smaller than those in the first and second embodiments by (n-1). The armature coils 4, 5, 6 are respectively provided with semiconductor switching elements 7,
8 and 9 are connected to each other to form a second main circuit, and the semiconductor switching elements 7, 8 and 9 are on / off controlled according to a preset order. Further, since the semiconductor switching element 21 is on / off controlled in synchronization with the switching of the semiconductor switching element in the above-mentioned second main circuit, its switch timing is as shown in FIG. A diode 24 is connected in parallel with the second main circuit in order to form a loop circuit that discharges the inductive energy of the armature coil when the semiconductor switching element is turned off.

FIG. 5 is a sectional view showing the structure of a switched reluctance motor. Salient poles 51 to 56 are arranged on the inner circumference of a cylindrical yoke 50, and each salient pole has an armature. The coils a ₁ , a ₂ , a _n , b ₁ , b ₂ , b _n are attached to form a stator. A rotor 60 having eight salient poles is fixed to the rotating shaft 70, and the inner peripheral surfaces of the salient poles 51 to 56 of the stator are rotated via a gap.

[0015]

As is apparent from the above description, the drive circuit of the switched reluctance motor according to the present invention is generated when the semiconductor switching element for controlling the on / off currents of the n armature coils is off. The discharge circuit that regenerates the inductive energy of the armature coil to the DC power source through the parallel capacitor is composed of a simple circuit with few parts. Since a parallel capacitor in the discharge circuit can use an aluminum electrolytic capacitor having a large amount of low ripple, downsizing and cost reduction can be realized. Further, since the charging energy for the parallel capacitor described above is rapidly discharged by using the DC-DC converter, it is possible to shorten the ON / OFF cycle of the semiconductor switching element. Therefore, it is possible to realize an economical drive circuit and increase the rotation speed of the switched reluctance motor by accelerating the switching cycle.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment.

FIG. 2 is a waveform diagram in the first embodiment.

FIG. 3 is a block diagram showing a second embodiment.

FIG. 4 is a waveform diagram in the second embodiment.

FIG. 5 is a cross-sectional view of a switched reluctance motor.

FIG. 6 is a block diagram of a conventional switched reluctance motor.

[Explanation of symbols]

1,2,3,7,8,9,21,23 Semiconductor switching element 4,5,6 Armature coil 10 Parallel capacitor 11 DC power supply 13 Reactor 12, 14, 15-20, 24 Diode

Claims (4)

[Claims] 1. A first main circuit formed by serially connecting two semiconductor switching elements, which are respectively connected to the positive side and the negative side of a DC power source via an armature coil, is provided in an n-piece switch reluctance motor. And an auxiliary circuit formed by connecting to the plus side of the DC power supply through a parallel circuit composed of a semiconductor switching element (23) and a diode (4) and a reactor (13), and the DC power supply. To the minus side of each of the n first main circuits, the connection points of each of the two semiconductor switching elements and the armature coil are connected via a diode, respectively, and the auxiliary circuit and the minus side of the DC power source are connected. A switched circuit is formed by connecting a parallel capacitor (10) between The drive circuit of the reluctance motor. 2. The first n units are arranged in a preset order.
Is a method for controlling a drive circuit of a switched reluctance motor, in which two semiconductor switching elements in the main circuit are simultaneously turned on / off to sequentially switch the current supply to the armature coil in the first main circuit. , N when the respective two semiconductor switching elements in the first main circuit are simultaneously turned off, the inductive energy of the armature coil in the first main circuit is connected to both ends of the armature coil. When the parallel capacitor (10) is charged through the diode and the auxiliary circuit and the charging voltage becomes higher than the DC power supply voltage and becomes equal to or higher than a preset voltage, the semiconductor switching element (23) and the diode in the auxiliary circuit are charged. (14) and reactor (1
The switch according to claim 1, wherein the charging energy of the parallel capacitor (10) is regenerated by the DC power supply through the parallel circuit composed of 3) and the DC-DC converter composed of the parallel capacitor (10). A method for controlling a drive circuit of a de reluctance motor. 3. N armature coils connected in parallel via semiconductor switching elements (21) connected in series to the positive side of the DC power supply, and n semiconductor switching elements connected in parallel to the negative side of the DC power supply. Are connected in series to provide n second main circuits, and the semiconductor switching element (23) and the diode (1
4) and a reactor (13) via a parallel circuit connected to the positive side of the DC power source in an auxiliary circuit formed in the second main circuit of n connecting armature coils and semiconductor switching elements And a parallel capacitor (10) inserted between the auxiliary circuit and the negative side of the DC power source, with a diode (24) connected in parallel at both ends of an arbitrary second main circuit.
A drive circuit for a switched reluctance motor, wherein a discharge circuit for inductive energy of an armature coil is formed by and. 4. The semiconductor switching elements in the n second main circuits are on / off controlled according to a preset order, and the semiconductor switching elements (21) are provided in the n semiconductors in the second main circuit. A method of controlling a drive circuit of a switched reluctance motor, which sequentially switches current supply to n armatures in the second main circuit by performing on / off control in synchronization with operations of switching elements, respectively. , N when the respective semiconductor switching elements in the second main circuit are turned off, the inductive energy of each armature coil in the second main circuit is connected to one end of the armature coil and a diode connected to one end of the armature coil. A parallel capacitor (10) via a diode (24) connected in parallel to both ends of the second main circuit and an auxiliary circuit. When the battery is charged and the charging voltage becomes higher than the DC power supply voltage and becomes equal to or higher than a preset voltage, the parallel circuit including the semiconductor switching element (23), the diode (14) and the reactor (13) in the auxiliary circuit. The drive of the switched reluctance motor according to claim 3, wherein the direct-current power source regenerates the charging energy of the parallel capacitor (10) through a DC-DC converter including the parallel capacitor (10). Circuit control method.