JP2001309691A - Switched reluctance motor and its sensorless drive circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the sensorless drive circuit of a switched reluctance motor eliminating need of using the position detection sensor of a rotor pole and a previously calculated energization pattern the switched reluctance motor used for the sensorless drive circuit. SOLUTION: When as shown in Figure 7c a rotor pole 2b is positioned in the substantial intermediate of the stator pole 4d of a C phase and an A phase being two non-excitation phases in a state where a B phase is excited, A phase voltage is substantially equal to C phase voltage, and the voltage difference is 0 volt. When the voltage difference is smaller than a prescribed value, a commutation instruction is output, and the excitation phase is changed over from the B phase to the C phase as shown in Figure 7 (d), and an SR motor 1 continues rotation in the right-hand direction. In other words, the SR motor can be driven with no-sensor by the voltage difference of the armature coil voltage of the non-excitation phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sensorless drive circuit for a switched reluctance motor and a switched reluctance motor used in the sensorless drive circuit.

[0002]

2. Description of the Related Art Conventionally, a drive circuit of a switched reluctance motor (hereinafter, referred to as an “SR motor”) uses a sensor such as a rotary encoder, and the sensor detects the position of a rotor pole and a predetermined position. The commutation is performed at the timing described above, and the SR motor is driven.

[0003]

However, when such a rotor pole position detection sensor is used in a drive circuit of an SR motor, the circuit cost increases. If the sensor fails, the SR motor cannot be driven. Further, the sensor occupies a space in the housing of the SR motor together with the conductors attached to the sensor, so that it is difficult to reduce the size of the SR motor.

On the other hand, the relationship between the position of the rotor pole of the SR motor and the inductance value (or the armature current value) is measured in advance, and the optimum energization pattern for the inductance value is calculated and stored. In some cases, the SR motor is driven sensorlessly using this energization pattern. However, in such a method, since the energization pattern must be calculated and stored in advance, not only is it difficult to calculate the energization pattern itself, but also a separate circuit for storing the energization pattern is required. There is a problem that the circuit cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a sensorless drive circuit for a switched reluctance motor that does not use a rotor pole position detection sensor or a previously calculated energizing pattern. It is an object of the present invention to provide a switched reluctance motor used in the sensorless drive circuit.

[0006]

In order to achieve this object, a sensorless drive circuit according to the first aspect of the present invention includes a stator having a plurality of armature windings wound thereon, and a rotatable interior of the stator. A phase-excitation circuit that sequentially excites the armature windings of the plurality of phases, and a non-excitation that is not excited by the phase excitation circuit. An electromotive force detection circuit for detecting a phase transformer electromotive force, and a commutator for performing commutation by switching an excitation phase of the phase excitation circuit in accordance with the non-excitation phase transformer electromotive force detected by the electromotive force detection circuit. And a flow circuit.

According to the sensorless drive circuit of the switched reluctance motor of the first aspect, any one of the phases of the armature winding is excited by the phase excitation circuit, and the excitation is not performed by the phase excitation circuit. A transformer electromotive force in a non-excited phase is detected by an electromotive force detection circuit. The commutation circuit performs commutation by switching the excitation phase of the phase excitation circuit in accordance with the non-excitation phase transformer electromotive force detected by the electromotive force detection circuit. As a result, the switched reluctance motor is driven without a sensor.

A sensorless drive circuit for a switched reluctance motor according to a second aspect of the present invention is the sensorless drive circuit according to the first aspect, wherein the electromotive force detection circuit includes two or more non-excitation circuits that are not excited by the phase excitation circuit. A voltage difference detection circuit for detecting a voltage difference of the transformer electromotive force of the excitation phase, and outputting a commutation command to the commutation circuit when the voltage difference detected by the voltage difference detection circuit becomes a predetermined value or less. A commutation command circuit.

A sensorless drive circuit for a switched reluctance motor according to claim 3 is the sensorless drive circuit according to claim 1 or 2, wherein the voltage difference detection circuit is
A differential amplifier for calculating a voltage difference between the two or more non-excited phase transformer electromotive forces; and a voltage doubler rectifier circuit for rectifying the output voltage of the differential amplifier in the positive direction. Therefore, the voltage difference between the two or more non-excited phase transformer electromotive forces is calculated by the differential amplifier and then rectified in the positive direction by the voltage doubler rectifier circuit, so that the voltage difference always becomes a positive voltage value. Therefore, the comparison as to whether or not the voltage difference is equal to or less than the predetermined value can be performed using the threshold value of the positive voltage, and thus the comparison of the voltage difference can be easily performed.

A sensorless drive circuit for a switched reluctance motor according to a fourth aspect of the present invention is the sensorless drive circuit according to any one of the first to third aspects, wherein the phase excitation signal output from the phase excitation circuit is pulse width modulated. A pulse width modulation circuit for adjusting the rotation speed of the switched reluctance motor. With this pulse width modulation circuit, the rotational speed of the switched reluctance motor can be adjusted, and an AC component can be added to the phase excitation signal to easily detect the transformer electromotive force in the non-excitation phase.

According to a fifth aspect of the present invention, there is provided a switched reluctance motor for use in the sensorless drive circuit according to any one of the first to fourth aspects.
The above-mentioned armature windings of the same phase have two or more armature windings of the same phase, and the armature windings of the same phase have the same polarity when excited by the phase excitation circuit. It is wound.

[0012]

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a simplified diagram showing a configuration of a switched reluctance motor (hereinafter, referred to as an “SR motor”) of the present embodiment. The SR motor 1 is configured by rotatably supporting a rotor 2 fixed to a rotating shaft 3 in a stator 4. The rotor 2 includes a circular boss 2 a fixed to the rotating shaft 3 and the boss 2
and four rotor poles 2b radially protruding at equal intervals in the circumferential direction of FIG. The stator 4 has six stator poles 4 protruding at equal intervals in the inner circumferential direction.
d.

The A-phase, B-phase
The three-phase armature windings 4a, 4b, 4c of phase C and phase C are wound two by two on the opposed stator pole 4d.
The opposed two-pole armature windings 4a to 4c are excited (energized) so that the stator poles 4d around which the armature windings 4a to 4c are wound have the same polarity of N pole or S pole. It is wound in the direction to excite. As a result, the leakage flux to the non-excited phase at the time of excitation is increased, and the detection of the transformer electromotive force in the non-excited phase is improved.

This point will be described with reference to FIG. FIG.
FIG. 2A is a diagram illustrating a state of a magnetic flux when an A-phase armature winding 4a is excited in the SR motor 1 according to the present embodiment, and FIG. 2B is a diagram illustrating an A-phase in a conventional SR motor. FIG. 5 is a diagram showing a state of magnetic flux when the armature winding of FIG. As shown in FIG. 2, in the SR motor 1 of the present embodiment,
Since the excited A-phase stator pole 4d is excited to the N-pole of the same polarity, the magnetic flux 5 generated by the excitation enters from the rotor pole 2b facing the A-phase armature winding 4a.
It passes through another rotor pole 2b, enters the B-phase and C-phase stator poles 4d, which are the non-excited stator poles 4d, and returns to the A-phase stator pole 4d.

On the other hand, as shown in FIG. 2B, in the conventional SR motor, the excited A-phase stator pole is
Since one is excited to the N-pole and the other to the S-pole, the magnetic flux 5 generated by the excitation enters the opposite rotor pole from the A-phase stator pole excited by the N-pole, and further from the rotor pole to the S-pole.
It enters the A-phase stator pole excited by the pole and returns to the original N-pole excited stator pole, and there is almost no leakage flux to the non-excited B-phase and C-phase stator poles.

As is apparent from a comparison between the two, in the SR motor 1 of the present embodiment, the armature windings 4a to 4c are so excited that the stator poles 4d are excited to the same polarity of the N pole or the S pole. Since it is wound, it is possible to increase the leakage flux to the non-excitation phase at the time of excitation. When the leakage magnetic flux increases, the rotation efficiency of the motor deteriorates, but the transformer electromotive force in the non-excited phase can be detected satisfactorily, and the sensorless drive of the SR motor 1 can be reliably performed.

FIG. 3 is a block diagram showing a schematic configuration of the sensorless drive circuit of the present embodiment. As shown in FIG. 3, the sensorless drive circuit 10 mainly includes a speed adjustment circuit 11, a phase excitation circuit 12, and a sensorless control circuit 13. The speed adjusting circuit 11 is a known pulse width modulation circuit (PWM (Pulse Width Modulation) circuit) for outputting a rectangular wave oscillating at a predetermined duty ratio, and includes a variable resistor (not shown) provided in the circuit. By changing the value, the duty ratio of the output rectangular wave is changed, and the rotation speed of the SR motor 1 is adjusted.

The phase excitation circuit 12 is constituted by an inverter circuit shown in FIG. FIG.
Excitation circuit 1 showing phase armature windings 4a to 4c together
2 is a circuit diagram of FIG. Phase excitation circuit (inverter circuit) 12
Are armature windings 4a to 4c of three phases (A phase, B phase, C phase)
A circuit for sequentially switching energization (excitation) of a 24 volt DC voltage. The emitter terminals of three PNP transistors Qu1, Qv1, and Qw1 as upper arm transistors are connected to the plus side terminal of the DC power supply 21 of the phase excitation circuit 12, and the ground side terminal of the DC power supply 21 is
The source terminals of three N-MOS field effect transistors Qx1, Qy1, and Qz1 as lower arm transistors are connected, and these are used to form three-phase armature windings 4a to 4c.
Are formed. That is, the three-phase armature windings 4a to 4c are connected between the collector terminals of the upper arm transistors Qu1 to Qw1 and the drain terminals of the lower arm transistors Qx1 to Qz1, respectively.

Between the bases and the emitters of the upper arm transistors Qu1 to Qw1, 4.7 kΩ resistors Ru1 to Rw1 for protection and prevention of floating of the base voltage are connected.
1 base terminal has a resistance Ru2 of 180Ω (2W).
One end of Rw2 is connected, and the other ends of the resistors Ru2 to Rw2 are connected to the collector terminals of NPN transistors Qu2 to Qw2. The emitter terminals of the transistors Qu2 to Qw2 are grounded, and 10 kΩ resistors Ru3 to Rw3 are connected between their base and emitter. Further, one ends of 4.7 kΩ resistors Ru4 to Rw4 are connected to base terminals of the transistors Qu2 to Qw2. The other ends of the resistors Ru4 to Rw4 are used as input terminals of the phase excitation circuit 12 as sensorless control circuits 13 to be described later.
And the upper arm transistors Qu1 to Qw1 are turned on or off according to the output of the sensorless control circuit 13.

Between the gates and sources of the lower arm transistors Qx1 to Qz1, 10 kΩ resistors Rx1 to Rz1 for protection and prevention of floating of the gate voltage are connected. Further, the gate terminals of the lower arm transistors Qx1 to Qz1 are connected to the output terminals a to c of the sensorless control circuit 13 via the 1 kΩ resistors Rx2 to Rz2, and the NPN transistor Qx as a chopper driver.
2 to Qz2. The transistors Qx2 to Qz2 have their emitter terminals grounded,
10 kΩ resistors Rx3 to Rz between the base and the emitter
3 is connected, so-called open collector type NPN
It is a digital transistor. The base terminals of the transistors Qx2 to Qz2 have a resistance Rx4 of 10 kΩ.
To the output terminal of the speed adjustment circuit (PWM circuit) 11 through Rz4. Therefore, the lower arm transistors Qx1 to Qz1 are turned on or off according to the output of the sensorless control circuit 13 and the output of the speed adjustment circuit (PWM circuit) 11. Specifically, the lower arm transistor Q
x1 to Qz1 are turned on only when a high signal is output from the sensorless control circuit 13 and a low signal is output from the speed adjustment circuit 11 to turn off the transistors Qx2 to Qz2.

As described above, a rectangular wave having a predetermined duty ratio is output from the speed adjusting circuit 11, so that the lower arm transistors Qx1 to Qz1 can adjust the speed while the upper arm transistors Qu1 to Qw1 are on. Circuit 1
On / off is repeated at a duty ratio of 1 square wave. The energization and non-energization of the armature windings 4a to 4c are switched in conjunction with the on / off of the lower arm transistors Qx1 to Qz1. Therefore, an AC component necessary for detecting the transformer electromotive force in the non-excitation phase can be generated by the speed adjustment circuit 11 configured by the pulse width modulation circuit.

The upper arm transistors Qu1 to Qw
1 between the collector and the emitter and between the sources and the drains of the lower arm transistors Qx1 to Qz1 with the armature windings 4a to 4c of the SR motor 1 interposed therebetween when the arm transistors Qu1 to Qz1 are turned on or off. Freewheel diodes Du to Dz for circulating the current caused by the back electromotive force generated in the slave windings 4a to 4c
Are connected in antiparallel, respectively.

As shown in FIG. 3, the sensorless control circuit 1
3 is a rotor tooth position detection circuit 14, a commutation circuit 15,
And a phase excitation signal output circuit 16. FIG.
4 is a circuit diagram of a rotor tooth position detection circuit 14 of the sensorless control circuit 13. FIG. The rotor tooth position detection circuit 14
When a high signal is being input from the third input terminal IN3, the voltage input to the first input terminal IN1 and the second input terminal I
When the voltage difference from the voltage input to N2 becomes equal to or less than a predetermined value, the circuit outputs a signal that maintains a low level for a certain period of time. First, the rotor tooth position detection circuit 14 will be described with reference to FIG.

The first input terminal I of the rotor tooth position detecting circuit 14
One end of a 270Ω resistor R1 is connected to N1. The other end of the resistor R1 is connected to one end of a 100 kΩ resistor R2 whose other end is grounded. It is connected. Similarly, the second input terminal I
One end of a 270Ω resistor R3 is connected to N2. The other end of the resistor R3 is connected to one end of a 100 kΩ resistor R4 whose other end is grounded. It is connected.

The differential amplifier 22 is a circuit for calculating the voltage difference between the voltage input to the first input terminal IN1 and the voltage input to the second input terminal IN2.
It has an operational amplifier OP with the negative voltage set to -15 volts and 15 volts. One end of each of a 1 kΩ resistor R5 and a resistor R6 and a 100 pF capacitor C1 whose other end is grounded are connected to the negative input terminal of the operational amplifier OP. The other end of the resistor R5 is connected to one end of the resistor R1, and the resistor R6 is connected as a feedback resistor and the other end is connected to the output terminal of the operational amplifier OP. One terminal of each of a resistor R7 and a resistor R8 of 1 kΩ and a capacitor C2 of 100 pF whose other end is grounded are connected to a positive input terminal of the operational amplifier OP. The other end of the resistor R7 is connected to the resistor R3 described above.
And the other end of the resistor R8 is grounded.

As described above, each resistor R5 of the differential amplifier 22
Since the resistance values of .about.R8 are all 1 k.OMEGA., The voltage difference between the resistors R4 and R2 is output from the differential amplifier 22 as it is. The resistance values of the resistors R5 to R8 are adjusted so that the differential amplifier 22 outputs the resistors R4 and R2.
May be amplified and output.

The output terminal of the differential amplifier 22 is connected to the input terminal of the voltage doubler rectifier circuit 23. Voltage doubler rectifier 23
Is a circuit for rectifying the output voltage of the differential amplifier 22 from -15 volts to +15 volts in the positive direction from 0 volts to +30 volts. One end of a 47 nF capacitor C3 is Input end. The other end of the capacitor C3 is connected to the cathode terminal of the diode D1 whose anode terminal is grounded and to the anode terminal of the diode D2. The cathode terminal of the diode D2 is connected to a 3.3 nF capacitor C4 having the other end grounded.
And a 1.8 kΩ resistor R, also grounded at the other end.
9 and as an output terminal of the voltage doubler rectifier circuit 23, to the positive input terminal of the comparator CP.

The comparator CP is for comparing whether or not the voltage difference between the voltage input to the first input terminal IN1 and the voltage input to the second input terminal IN2 is smaller than a predetermined value. A threshold value setting circuit 24 for setting a “threshold value” for comparison is connected to a negative input terminal of the comparator CP.

The threshold value setting circuit 24 has one end connected to the +
It has a resistor R10 of 68 kΩ connected to 24 volts, and the other end of the resistor R10 is connected to one end of a variable resistor VR whose resistance value can be changed in a range of 0 to 27 kΩ. The other end of the variable resistor VR is grounded, and the resistor R10 and the variable resistor VR are connected in parallel by 47 μF.
Capacitors C5 and C6 are connected. Variable resistance V
The non-ground terminal of R, that is, the connection terminal between the variable resistor VR and the resistor R10 is connected to the minus input terminal of the comparator CP as the output terminal of the threshold value setting circuit 24. Therefore, by adjusting the resistance value of the variable resistor VR, the “threshold value” output to the comparator CP can be changed.

The output voltage of the differential amplifier 22 is rectified in the positive direction by the voltage doubler rectifier circuit 23, and the rectified voltage value is compared by the comparator CP. The output voltage of the threshold setting circuit 24 can be adjusted within a positive voltage range. Therefore,
The circuit configuration of the threshold value setting circuit 24 can be simplified.

The output terminal of the comparator CP is pulled up to +5 volts of a power supply through a 56 kΩ resistor R11 and is connected to the B terminal of the monostable multivibrator MM. Monostable multivibrator MM is CD
When the input signal of the terminal B falls while the high signal is being input to the terminal, the capacitance of the capacitor C7 and the resistance R1
A signal that keeps low for a predetermined time determined by the resistance value of
Output from Q bar terminal. The CD terminal is connected to the third input terminal IN
3 and the Q bar terminal is an output terminal OUT of the rotor tooth position detection circuit 14. That is, the signal output from the Q bar terminal is a commutation command output to the commutation circuit 15 (see FIGS. 3 and 6). Note that the capacitance of the capacitor C7 is 0.1 μF, and the resistance value of the resistor R12 is 2.2 MΩ.

As described above, the rotor tooth position detection circuit 14
When a high signal is being input from the third input terminal IN3, the voltage input to the first input terminal IN1 and the second input terminal I
When the voltage difference from the voltage input to N2 becomes a predetermined value or less, a signal (commutation command) for maintaining low for a predetermined time is output.

FIG. 6 shows the rotor tooth position detecting circuit 1 described above.
FIG. 4 is a circuit diagram of a sensorless control circuit 13 including three sets 4. During the excitation of the C-phase armature winding 4c, the three sets of rotor tooth position detection circuits 14 provide the A-phase and B-phase armature windings 4a,
(B) comparing the electromotive force of the transformer 4b with the transformer electromotive force of the armature windings 4b and 4c of the B-phase and C-phase while exciting the armature winding 4a of the A-phase And (14
a) comparing the electromotive force of the transformers of the C-phase and A-phase armature windings 4c and 4a during excitation of the B-phase armature winding 4b, and (14b).

The plus side end u of the A-phase armature winding 4a is provided at the first input end IN1 of the rotor tooth position detection circuit 14c, and the plus side end u of the B-phase armature winding 4b is provided at the second input end IN2. The terminal v is connected to the third input terminal IN3.
The output terminals c of the sensorless control circuit 13 for c are connected to each other. This rotor tooth position detection circuit 14c
Is input to one end of a two-input OR1. The output terminal of the OR1 is connected to the B terminal of the monostable multivibrator MM1. Also, the output terminal O
The UT is also connected to the CD terminal of the monostable multivibrator MM3.

Similarly, the plus side end v of the B-phase armature winding 4b is provided at the first input terminal IN1 of the rotor tooth position detecting circuit 14a, and the C-phase armature winding 4c is provided at the second input terminal IN2. And the third input terminal IN3 has an output terminal a of the sensorless control circuit 13 for the A-phase armature winding 4a.
Are connected respectively. The output terminal OUT of the rotor tooth position detection circuit 14a is input to one end of a two-input OR2, and the output terminal of the OR2 is connected to the B terminal of the monostable multivibrator MM2. The output terminal OUT is also connected to the CD terminal of the monostable multivibrator MM1.

Further, the first of the rotor tooth position detection circuits 14b
The plus end w of the C-phase armature winding 4c is connected to the input end IN1.
However, the plus end u of the A-phase armature winding 4a is provided at the second input end IN2, and the output end b of the sensorless control circuit 13 for the B-phase armature winding 4b is provided at the third input end IN3.
Are connected respectively. The output terminal OUT of the rotor tooth position detection circuit 14b is input to one end of a two-input OR3, and the output terminal of the OR3 is connected to the B terminal of the monostable multivibrator MM3. The output terminal OUT is also connected to the CD terminal of the monostable multivibrator MM2.

The monostable multivibrators MM1 to MM3
When a high signal is input to the CD terminal and the input signal at the B terminal falls, the capacitors C11 to C1
A signal for maintaining a low level for a predetermined period of time determined by the capacitance 3 and the resistance values of the resistors R21 to R23 is output from the Q bar terminal. The capacitance of each of the capacitors C11 to C13 is 100 μF, and the resistance value of each of the resistors R21 to R23 is 2.2 MΩ.

A switch SW for switching between operation (drive) and stop of the SR motor 1 is connected to the other input terminal of each of the two-input ORs OR1 to OR3. This switch SW
Is connected to the 5 volt side of the power supply, the SR motor 1 stops, and conversely, when the
Starts operation (driving).

The Q bar terminal of the monostable multivibrator MM1 is connected to the input terminal of a three-input OR11. Output terminals b and c of the sensorless control circuit 13 for the B-phase and C-phase armature windings 4b and 4c are respectively connected to the other two input terminals of the OR OR11. Is connected to the input terminal of the inverter IV1. The output terminal of the inverter IV1 further includes:
It is connected to the input terminal of a two-input OR 21 and its OR
Another input terminal 21 is connected to the switch SW described above. The output terminal of the OR 21 is the output terminal a of the sensorless control circuit 13 for the A-phase armature winding 4a.

The Q bar terminal of the monostable multivibrator MM2 is connected to the input terminal of the three-input OR12. The other two inputs of this OR 12 have A
The output terminals a and c of the sensorless control circuit 13 are connected to the phase and C-phase armature windings 4a and 4c, respectively, and the output terminal of the OR 12 is connected to the input terminal of the inverter IV2. The output terminal of the inverter IV2 is
Furthermore, it is connected to the input terminal of a two-input OR22, and the other input terminal of the OR22 is connected to a Q terminal of a monostable multivibrator MM4 described later. The output terminal of the OR 22 is the output terminal b of the sensorless control circuit 13 for the B-phase armature winding 4b.

Further, the Q bar terminal of the monostable multivibrator MM3 is connected to the input terminal of a three-input OR13. The other two input terminals of this OR 13 are A
The output terminals a and b of the sensorless control circuit 13 are connected to the phase and B phase armature windings 4a and 4b, respectively, and the output terminal of the OR 13 is connected to the input terminal of the inverter IV3. The output terminal of the inverter IV3 is
Sensorless control circuit 13 for C-phase armature winding 4c
Output terminal c.

The monostable multivibrator MM4 has a CD
Since the terminal is connected to +5 volts of the power supply, when the input signal at the terminal B falls, a signal that maintains high for a predetermined time determined by the capacitance of the capacitor C14 and the resistance value of the resistor R24 is output from the Q terminal. . The capacitance of the capacitor C14 is 47 μF, and the resistance value of the resistor R24 is 120 kΩ. The B terminal of the monostable multivibrator MM4 is connected to the switch SW described above. When the switch SW is switched from “stop (5v)” to “operation (0v)”, a falling signal is input to the B terminal. Is done. As a result, a signal that maintains a high level for a predetermined time is output from the Q terminal, whereby excitation is started from the B-phase armature winding 4b, and the SR motor 1 starts rotating.

In the sensorless control circuit 13, the commutation circuit 15 includes ORs OR1 to OR3 and monostable multivibrators MM1 to MM3, and the phase excitation signal output circuit 16 includes ORs OR11 to OR13, O
R21, OR22, inverters IV1 to IV3, and a monostable multivibrator MM4.

Next, the operation of the sensorless drive circuit 10 configured as described above will be described with reference to FIGS. FIG. 7 is a diagram showing the excitation of the armature windings 4a to 4c and the manner in which the rotor 2 rotates with the excitation. FIG. 8 shows the sensorless drive circuit 10 when the SR motor 1 is driven. It is a timing chart.

First, when the switch SW is "stop", the output a of the OR 21 becomes high. as a result,
When a high is input to the OR 12 and a low is output from the inverter IV2, the monostable multivibrator M
Since the row is output from the Q terminal of M4, OR OR
The output b of 22 is low. Further, since the output of the OR OR 21 becomes high, a high is input to the OR OR 13 and the output c of the inverter IV3 becomes low. Therefore, when the switch SW is “stopped”, the A-phase armature winding 4
a is excited, and the SR motor 1 is stopped in the state shown in FIG.

Next, when the switch SW is switched from "stop" to "operation", the monostable multivibrator MM4
Since the input signal at the terminal B falls, a high signal is output from the terminal Q for a predetermined time, and the output b of the OR gate 22 becomes high. As a result, a high is input to the OR OR11, a low is output from the inverter IV1, and a low is output from the switch SW.
The output a of 1 becomes low. Further, since the output of the OR OR 22 becomes high, a high is input to the OR OR 13 and the output c of the inverter IV3 becomes low. Therefore, when the switch SW is switched from "stop" to "operation", the B-phase armature winding 4b is excited. Thereby, the SR motor 1
Of the rotor 2 starts rotating leftward in FIG.

While the B-phase armature winding 4b is being excited, the rotor tooth position detecting circuit 1 of the three sets of rotor tooth position detecting circuits 14 whose high is input to the third input terminal IN3.
Only 4b is valid. In the rotor tooth position detecting circuit 14b, the C-phase and A-phase armature windings 4c and 4
The voltage difference due to the transformer electromotive force occurring at a is compared. That is, in FIG. 5, a C-phase armature winding voltage (hereinafter abbreviated as “C-phase voltage”) is input to a first input terminal IN1, and an A-phase armature winding voltage (hereinafter, referred to as “C-phase voltage”) is input to a second input terminal IN2. "A phase voltage"
Is abbreviated). The voltage difference between the two input voltages is calculated by the differential amplifier 22 as (A phase voltage) − (C phase voltage). The calculated voltage difference is rectified by the next stage voltage doubler rectifier circuit 23 to a positive voltage of 0 volt or more, and thereafter, the “threshold (voltage value)” set by the threshold setting circuit 24. Be compared.

When the B-phase armature winding 4b is excited, the rotor 2 rotates to the left, and the state shown in FIG. 7A is changed to the state shown in FIG. 7B. As shown in FIG. 7B, when the rotor pole 2b is located closer to the A-phase stator pole 4d than the C-phase among the two non-excited phases C and A, the A-phase voltage Is larger than the C-phase voltage (A-phase voltage> C-phase voltage). The voltage difference between the A-phase voltage and the C-phase voltage in this state, that is, the output voltage of the voltage doubler rectifier circuit 23 is larger than the “threshold value” set by the threshold value setting circuit 24, and the output of the comparator CP Is high, and the output of the Q-bar terminal of the monostable multivibrator MM remains high.

From the state shown in FIG. 7B, the rotor 2 further rotates counterclockwise, and as shown in FIG.
When it is located substantially in the middle between the C-phase and A-phase stator poles 4d, which are the two non-excited phases, the A-phase voltage and the C-phase voltage are substantially equal (A-phase voltage ≒ C-phase voltage), and the voltage difference is substantially zero. Become a bolt. Then, the voltage difference between the A-phase voltage and the C-phase voltage rectified in the positive direction by the voltage doubler rectifier circuit 24 becomes smaller than the “threshold value” of the threshold value setting circuit 24, and the output of the comparator CP changes from high. Fall to Row. When this falling signal is input to the B terminal of the monostable multivibrator MM, a signal that maintains a low level for a predetermined time is output from the Q bar terminal. This signal is a commutation command.

When the commutation command is output, the CD terminal of the monostable multivibrator MM2 in FIG. 6 goes low.
A high signal is output from the Q bar terminal to the OR OR 12. As a result, the output of the inverter IV2 becomes low, the output b of the OR OR 22 switches from high to low, and the excitation of the B-phase armature winding 4b ends. This is because the Q terminal of the monostable multivibrator MM4 outputs low.

When the commutation command is output, OR OR
3 falls, monostable multivibrator MM
A signal for maintaining a low level for a predetermined time is output from the Q bar terminal of No. 3. Since the outputs a and b at this time are low, the inputs of the OR OR 13 are all low, and the low is input to the inverter IV3. As a result, inverter I
V3 becomes a high output, and the C-phase armature winding 4c is excited.

As described above, commutation is performed according to the rotation of the rotor 2, and the excitation phases are A-phase, B-phase, C-phase, A-phase,.
The order is switched in the order of Fig. 7 (a), (b), ...
(F), (a),..., The SR motor 1 rotates to the left. As described above, according to the drive circuit 10 of the present embodiment, the transformer electromotive force generated in the non-excitation phase is used, that is, by the voltage difference between the armature winding voltages in the non-excitation phase,
The SR motor 1 can be driven without a sensor.

When the switch SW is switched from "run" to "stop", the output a of the OR 21 becomes high as described above, and as a result, the OR 1
Since the high is input to 2 and the low is output from the inverter IV2 and the low is output from the monostable multivibrator MM4, the output b of the OR 22 is low. Also, since the output of OR 21 becomes high,
High is input to the OR 13 and the output c of the inverter IV3 becomes low. Therefore, the SR motor 1 stops in a state where the A-phase armature winding 4a is excited, that is, in a state shown in FIG.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. Can easily be inferred.

[0055]

According to the sensorless drive circuit of the switched reluctance motor of the present invention, commutation is performed according to the transformer electromotive force of the non-excited phase, and the switched reluctance motor can be driven sensorlessly. Therefore, since it is not necessary to use a rotor pole position detection sensor, there is an effect that the circuit cost can be reduced and the size of the switched reluctance motor can be reduced.
Further, since there is no need to calculate and store the energization pattern in advance, the work of calculating the energization pattern is eliminated, so that the development period of the motor drive circuit can be shortened and the development cost can be reduced. There is an effect that the circuit cost can be reduced by deleting.

According to the switched reluctance motor of the present invention, the armature windings of the same phase are wound around the stator so as to have the same polarity when excited by the phase excitation circuit. . Therefore, the leakage of the magnetic flux to the non-excited phase of the stator at the time of excitation increases, so that there is an effect that the transformer electromotive force of the non-excited phase can be detected well.

[Brief description of the drawings]

FIG. 1 is a simplified diagram showing a configuration of a switched reluctance motor (SR motor) according to an embodiment of the present invention.

FIG. 2 (a) shows A in the SR motor of the present embodiment.
FIG. 4 is a diagram illustrating a state of a magnetic flux when exciting a phase armature winding, and FIG. 4B is a diagram illustrating a state of a magnetic flux when exciting an A phase armature winding in a conventional SR motor; It is.

FIG. 3 is a block diagram showing a schematic configuration of a sensorless drive circuit according to one embodiment of the present invention.

FIG. 4 is a circuit diagram of a phase excitation circuit (inverter circuit).

FIG. 5 is a circuit diagram of a rotor tooth position detection circuit.

FIG. 6 is a circuit diagram of a sensorless control circuit.

FIGS. 7A to 7F are diagrams showing excitation of an armature winding and a state in which a rotor rotates with the excitation.

FIG. 8 is a timing chart of a sensorless drive circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Switch reluctance motor 2 Rotor (rotor) 4 Stator (stator) 4a, 4b, 4c Armature winding 10 Sensorless drive circuit 11 Speed adjustment circuit (PWM circuit) (pulse width modulation circuit) 12 Phase excitation circuit (inverter) Circuit) 14 rotor tooth position detection circuit (electromotive force detection circuit) 15 commutation circuit 16 phase excitation signal output circuit 22 differential amplifier (part of voltage difference detection circuit) 23 times voltage rectification circuit (part of voltage difference detection circuit) 24) Threshold value setting circuit (part of commutation command circuit) CP comparator (part of commutation command circuit) MM monostable multivibrator (part of commutation command circuit)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H550 BB04 DD09 FF03 GG01 HA01 HA07 HB16 LL17 5H619 AA13 BB01 BB06 BB24 PP01 PP13

Claims (5)

[Claims] 1. A sensorless drive circuit for a switched reluctance motor having a stator on which a multi-phase armature winding is wound, and a rotor rotatable within the stator, A phase excitation circuit for sequentially exciting the armature windings, an electromotive force detection circuit for detecting a transformer electromotive force in a non-excited phase that is not excited by the phase excitation circuit, and an electromotive force detection circuit for detecting the electromotive force. A commutation circuit for performing commutation by switching an excitation phase of the phase excitation circuit in accordance with a transformer electromotive force of a non-excitation phase, the sensorless drive circuit for a switched reluctance motor. 2. An electromotive force detection circuit comprising: a voltage difference detection circuit for detecting a voltage difference between two or more non-excited phases of a transformer electromotive force not excited by the phase excitation circuit; 2. The switched reluctance motor according to claim 1, further comprising: a commutation command circuit that outputs a commutation command to the commutation circuit when a voltage difference detected by the circuit becomes a predetermined value or less. Sensorless drive circuit. 3. The voltage difference detecting circuit according to claim 1, wherein the voltage difference detecting circuit calculates a voltage difference between the two or more non-excited phase transformer electromotive forces, and a voltage doubler for rectifying the output voltage of the differential amplifier in a positive direction. The sensorless drive circuit for a switched reluctance motor according to claim 1, further comprising a rectifier circuit. 4. A pulse width modulation circuit for controlling a rotation speed of the switched reluctance motor by pulse width modulation of a phase excitation signal output from the phase excitation circuit. 4. A sensorless drive circuit for a switched reluctance motor according to any one of claims 1 to 3. 5. The switched reluctance motor used in the sensorless drive circuit according to claim 1, wherein the armature winding has two or more same-phase armature windings. Wherein the two or more armature windings of the same phase are wound around the stator so as to exhibit the same polarity when excited by the phase excitation circuit. .