JP2001231270A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand the operation region of an electric motor by a simple circuit configuration and a control system in a device for driving the electric motor by an inverter circuit. SOLUTION: The inverter device is equipped with an electric motor that has an inverter circuit where a plurality of DC circuits consisting of two switching means are provided, and a plurality of stator coils that are connected to the output of the inverter, a capacitor that is connected to the input terminal of the inverter circuit, a DC power supply, a switching means that is connected to one end of the output of the DC power supply, and a control means that controls the switching means. In this case, the switching means changes the connection between one end of the output of the DC power supply and one end of the capacitor to that between the other of the output of the DC power supply and the connection part of the stator coils.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for driving a motor used for electric equipment used in ordinary households.

[0002]

2. Description of the Related Art The configuration of a conventional inverter device is shown in FIG.

Switching means 1, 2, 3, 4, 5, 6
Is composed of a parallel circuit of an IGBT which is a semiconductor element and a reverse connection diode.

The series circuit 7 is constituted by connecting the high-potential side switching means 1 and the low-potential side switching means 4 in series, and the high-potential side series circuit 8 is constituted by the switching means 2 and the low-potential side switching means 5. The series circuit 9 is configured such that the switching means 3 on the high potential side and the switching means 6 on the low potential side are connected in series.

[0005] The inverter circuit 10 is configured by connecting serial circuits 7 to 8 in parallel. That is, the switching means 1 to 6 are configured to be a three-phase bridge.

The motor 11 has a three-phase connected stator winding 1.
It comprises a stator 12 having 2u, 12v, and 12w and a rotor 13 having a permanent magnet.

The DC power supply 15 is configured to rectify an AC power supply by a rectifier circuit to obtain a DC voltage.

The rectifier circuit is configured to perform full-wave rectification using, for example, a diode bridge and a smoothing capacitor.

The control means 71 comprises a microcomputer, a plurality of logic circuits, and the like. The control means 71 controls on / off of predetermined switching means 1 to 6 according to the output logic of the position detecting means 18. At the same time, the control means 71 controls the energization ratio of the switching means 1 to 6 during the ON period. That is, in the inverter device of FIG. 9, by performing pulse width modulation (PWM), the stator windings 12u, 12v,
The average value of the applied voltage to 12w is controlled. In the inverter device shown in FIG. 9, the carrier frequency for performing the pulse width modulation is set to about 15.625 kHz.

The position detecting means 18 comprises three Hall ICs 19, 20, 21 for detecting the magnetic poles of the permanent magnet of the rotor 13.
The Hall ICs 19 to 21 output high or low to the control means 18 according to the magnetic pole of the permanent magnet. The Hall ICs 19 to 21 are arranged on the stator 12 so as to have an electrical angle of about 120 degrees.

The operation of the inverter device configured as described above will be described.

The ROM in the microcomputer constituting the control means 71 stores in advance the ON / OFF state of the switching means 1 to 6 according to the combination of the rotation direction of the electric motor 11 and the output logic of the Hall ICs 19 to 21,
Each time the logic of the Hall ICs 19 to 21 is switched, predetermined switching means 1 to 6 are turned on and off, and three-phase full-wave AC power is supplied to the motor 11 through the switching means 1 to 6. At the same time, the control means 71 detects the speed of the motor 11 during the high output period of the Hall IC 19 by means of a timer counter in the microcomputer, and performs PWM so that the speed of the motor 11 becomes a predetermined speed. Further, as another conventional example, although not shown, instead of performing PWM, the rectifier circuit may be configured as a booster circuit or a step-up / step-down circuit to vary the DC voltage output from the rectifier circuit. There are also things to do.

[0013]

As described above, the conventional inverter device controls the voltage applied to the electric motor by controlling the duty ratio of the switching means, so that it can be driven at a desired rotational speed. Is 1
In the state of 00%, it is not possible to drive at a higher speed. Therefore, in a device having a plurality of operating conditions, an over-specification motor or an inverter circuit having an extremely large unnecessary operation area is required. There was a problem that.

In another conventional inverter device, a rectifier circuit is configured as a step-up circuit or a step-up / step-down circuit to increase the voltage applied to the motor and expand the operating area of the motor. In order to provide the buck-boost circuit,
The control method becomes complicated, the number of parts increases, and there is a problem that the size of the apparatus is increased and the cost is increased.

The present invention has been made to solve the above-mentioned conventional problems, and has as its object to expand the operating area of a motor with a simple circuit configuration.

[0016]

In order to achieve the above object, the present invention provides an inverter circuit provided with a plurality of series circuits each including two switching means and a plurality of stator windings connected to an output of the inverter circuit. A motor connected to an input terminal of the inverter circuit, a DC power supply, switching means connected to one end of an output of the DC power supply, and control means for controlling the switching means. The connection between one end of the output of the DC power supply and one end of the capacitor and the connection between the one end of the output of the DC power supply and the connection between the stator windings are switched.

Thus, the maximum value of the voltage applied to the stator winding can be increased, so that the operating range of the motor can be extended to a high speed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION
An inverter circuit provided with a plurality of series circuits composed of two switching means and a motor having a plurality of stator windings connected to an output of the inverter circuit, a capacitor connected to an input terminal of the inverter circuit, a DC power supply, Switching means connected to one end of the output of the DC power supply, and control means for controlling the switching means, wherein the switching means includes a connection between one end of the output of the DC power supply and one end of the capacitor; The connection between one end of the output of the power supply and the connection between the stator windings is switched, and the maximum value of the voltage applied to the stator windings is switched about twice by the switching means. Therefore, when one end of the output of the DC power supply is connected to the connection between the stator windings by the switching means, the output of the DC power supply is output by the switching means. Compared with the case where one end is connected to one end of the output of said capacitor, it said can deliver up to about 400 times the power in each stator winding, can change the operating range of the motor.

According to a second aspect of the present invention, in the first aspect of the present invention, the motor has a permanent magnet in the rotor, and a relative position of the permanent magnet with respect to the stator winding. Wherein the control means controls the switching means in accordance with the output of the position detecting means, and the maximum value of the voltage applied to the stator winding is controlled by the switching means. When the one end of the DC power supply is connected to the connection between the stator windings by the switching means, one end of the output of the DC power supply is switched to the output of the capacitor by the switching means. The motor can be driven to a speed at which the induced electromotive force generated in the stator winding is about twice as compared with the case where the motor is connected to one end. Since the induced electromotive force is proportional to the speed of the electric motor, the speed of the electric motor can be approximately doubled at the maximum. Further, by providing a permanent magnet to the rotor, an inverter device for driving a highly efficient electric motor can be realized.

According to a third aspect of the present invention, in the first aspect of the present invention, the connecting portion between the plurality of stator windings constituting the DC motor and the motor is provided by the switching means. When connected, the control means turns off all the switching means on the potential side to which the switching means is connected. Since the regenerative current generated when the switching means is turned off can be reduced, the loss of the switching means is reduced. Can be suppressed. Further, since only one switching unit is turned on, the driving power of the switching unit can be suppressed.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the connecting portion between the plurality of stator windings constituting the DC motor and the motor is provided by the switching means. When connected, the control means turns on at least one of the switching means on the potential side connected to the switching means at least once, and a regenerative current generated when the switching means is turned off. However, when the switching means on the potential side opposite to the turned off switching means is turned on, the current flows to another stator winding through this switching means, so that the capacitor can be prevented from being excessively charged. Therefore, an inverter device with less failure due to overvoltage can be realized.

According to a fifth aspect of the present invention, in the first aspect of the present invention, when the target speed of the motor is within a predetermined speed, the switching means includes a DC power supply and one end of a capacitor. When the speed exceeds a predetermined speed, a connection between a plurality of stator windings constituting the motor and one end of the DC power supply are connected, and the motor is connected under a connection condition suitable for a target speed. It can be driven efficiently.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a circuit configuration of an inverter device according to Embodiment 1 of the present invention.

Switching means 1, 2, 3, 4, 5, 6
Are each composed of a parallel circuit of an IGBT and a reverse-connected diode capable of supporting high-frequency switching and large current capacity. However, the present invention is not limited to this, and a transistor or a MOSFET may be used instead of the IGBT.

The series circuit 7 is configured by connecting the switching means 1 on the high potential side and the switching means 4 on the low potential side in series. The series circuit 8 is configured by connecting the switching means 2 on the high potential side and the switching means 5 on the low potential side in series. The series circuit 9 is configured by connecting the switching means 3 on the high potential side and the switching means 6 on the low potential side in series.

The inverter circuit 10 includes series circuits 7, 8, 9
Are connected in parallel. That is, the inverter circuit 10 is configured such that the switching means 1, 2, 3, 4, 5, and 6 are three-phase bridged.

The motor 11 is a three-phase connected stator winding 1.
It comprises a stator 12 having 2u, 12v, and 12w and a rotor 13 having a permanent magnet.

The capacitor 14 is connected to the input terminal of the inverter circuit 10. The inverter circuit 10 receives DC power from the DC power supply 15 via the switching means 16 and supplies three-phase power to the motor 11.

The DC power supply 15 is configured to rectify the AC power by a rectifier circuit to obtain a DC voltage.

The rectifier circuit is configured to perform full-wave rectification using, for example, a diode bridge and a smoothing capacitor. However, this is merely an example, and two voltage smoothing capacitors may be connected in series, and this series circuit may be connected to a diode bridge to form a voltage doubler rectifier circuit.

The switching means 16 is constituted by a relay.
This relay is connected to a contact b by coil excitation, and is connected to a contact a by non-excitation. That is, by connecting to the contact a, the high-potential terminal of the capacitor 14 and the high-potential terminal of the DC power supply 15 are connected, and by connecting to the contact b, the stator windings 12u, 12v, and 12w are connected. Characteristics and DC power supply 1
5 is connected to the terminal on the high potential side. However, the connection of the DC power supply 15 may be switched by a mechanical latch type switch. In the present embodiment, the switching means 16 is provided with two contacts at points a and b, and the DC power supply 15 is always connected to the stator windings 12u, 12u.
v and 12w are connected to either the neutral point or the terminal on the high potential side of the capacitor. However, the present invention is not limited to this. For example, a third contact is newly provided, and the electric motor 11 is connected. When not driven, the terminal on the high potential side of the DC power supply 15 may be opened by connecting to this contact.

The control means 17 comprises a microcomputer, a plurality of logic circuits, and the like. In the present embodiment, the control means 17 controls on / off of the predetermined switching means 1, 2, 3, 4, 5, and 6 according to the output logic of the position detection means 18, and controls on / off of a relay as the switching means 16. .

The position detecting means 18 comprises three Hall ICs 19, 20, 21 for detecting the magnetic poles of the permanent magnet of the rotor 13.
The Hall ICs 19, 20, and 21 output high or low to the control means 18 according to the magnetic pole of the permanent magnet. Hall ICs 19, 20, and 21 have an electrical angle of about 120
It is arranged on the stator 12 so as to have an interval of degrees. In this case, for example, the position of the rotor 13 may be detected by detecting an induced electromotive force generated in the stator windings 12u, 12v, and 12w, or a rotary encoder or the like may be used.

The operation of the inverter device shown in FIG. 1 will be described.

The control means 17 controls the on / off of the switching means in accordance with the two states, that is, when the contact a provided on the switching means 18 is connected and when the contact b is connected.

In the present embodiment, the contact a
Are connected, and the high-potential-side output terminal of the DC power supply 15 is connected to the high-potential-side terminal of the capacitor 14.
The motor 11 is driven by the 120-degree conduction type full-wave drive according to the output logic of 19, 20, and 21. The on / off operation of the switching means 1, 2, 3, 4, 5, 6 with respect to the output logic of the Hall ICs 19, 20, 21 at this time will be described later with reference to FIG.

The contact b of the switching means 16 is connected, and the output terminal on the high potential side of the DC power supply 15 is connected to the stator windings 12u and 12u.
When the neutral points v and 12w are connected, the control means 17 drives the electric motor 11 with a 120-degree conducting half-wave according to the output logic of the Hall ICs 19, 20 and 21. At this time, the maximum applied voltage to the stator windings 12u, 12v, 12w is the output voltage of the DC power supply 15. Therefore, in the brushless DC motor in which the rotor 13 has a permanent magnet as in the present embodiment, the motor 11 can be driven to a higher speed region than when the contact point a is connected. This is for the following reason. Generally, in a brushless DC motor, an induced electromotive force is generated in proportion to the relative speed of the rotor 11 to the stator windings 12u, 12v, and 12w. A current is supplied to the stator windings 12u, 12v, 12w by the voltage of the difference between the induced electromotive force and the voltage applied to the stator windings 12u, 12v, 12w. Generates torque. However, in order to output the same torque, the current supplied to the stator windings 12u, 12v, and 12w also increases, so that the torque region is smaller than when the contact is connected to the contact a.

In this embodiment, when the contact b of the switching means 16 is connected, the connection between the capacitor 14 and the DC power supply 15 on the high potential side is cut off, and the stator windings 12u, 12v, 12w are connected.
The current path in which the induced electromotive force regenerated to the DC power supply 15 through the reverse connection diodes constituting the switching means 1, 2, 3 is cut off. As a result, torque in the direction opposite to the rotation direction of the electric motor 11 is not generated, so that the electric motor 11 can be driven efficiently. However, this alone does not allow the regenerative current generated when the switching means 4, 5, 6 is turned off to be absorbed by the DC power supply 1, so that the stator windings 12u, 1
An excessive voltage will be generated at 2v and 12w to make the regenerative current zero. In order to prevent this overvoltage, a capacitor 14 having a capacity capable of absorbing the regenerative current is provided. Although not particularly shown in FIG. 1, a resistor may be connected in parallel to the capacitor 14 for discharging, or a series circuit of a resistor and a switching element may be connected in parallel, and the voltage of the capacitor 14 may be changed by turning on and off the switching element. May be controlled.

FIG. 2 shows the speed-torque characteristics of the motor 11 when the contact a of the switching means 16 is connected and when the contact b is connected. (A) shows the speed-torque characteristics when the contact a of the switching means 16 is connected and the DC power supply 15 and the capacitor 14 are connected. (B) is the switching means 16
Are connected, the DC power supply 15 and the stator winding 12u,
It shows the speed-torque characteristics when the neutral points of 12v and 12w are connected. As shown in FIG. 2, when the torque is low, the motor can be driven to a higher speed when the contact b of the switching means 16 in FIG. 2B is connected. At low speeds, higher torque can be driven when the contact point a of the switching means 16 in FIG. This is achieved by switching the connection between the contact point a and the contact point b of the switching means 16 as described above, so that the stator winding 12u,
The maximum value of the applied voltage to 12v and 12w is switched to about twice, and the driving method of the electric motor 11 is also three-phase full-wave drive when the contact a is connected and three-phase half-wave drive when the contact b is connected. This is for switching.

As described above, the maximum value of the voltage applied to the stator windings 12u, 12v, and 12w is switched by the switching means 16, and the driving method of the motor 11 is switched between three-phase full-wave and three-phase half-wave. The operating area of the electric motor 11 can be changed. 1 and 2 show one embodiment of the first, second, third, fourth and fifth aspects of the present invention.

FIG. 3 shows the switching means 1 to 6 and the Hall ICs 19 to 2 when the contact a of the switching means 16 is connected.
1 shows waveforms of currents flowing through stator windings 12u, 12v, and 12w. When the contact point a of the switching means 16 is connected, the inverter device in the present embodiment drives the electric motor 11 by full-wave energized at 120 degrees. (A) Hall I
The output waveform of C19, (b) shows the output waveform of Hall IC 20, and (c) shows the output waveform of Hall IC 21.
(D) is an on / off state of the switching means 1, (e) is an on / off state of the switching means 2, (f) is an on / off state of the switching means 3, (g) is an on / off state of the switching means 4, and (h) is a switching means. 5 shows an on / off state, and (i) shows an on / off state of the switching means 6. (J) is a current waveform of the stator winding 12u,
(K) shows the current waveform of the stator winding 12v, and (l) shows the current waveform of the stator winding 12w. (J) (k)
In the current waveform (1), the direction of the arrow shown in FIG. 1, that is, the direction in which the switching means 1 to 3 flow when turned on is made positive. Each of the switching means 1 to 6 is turned on for a period of 120 electrical degrees. Control means 17
The combination of ON / OFF of the switching means 1 to 6 corresponding to the logic of the output signal of the Hall ICs 19 to 21 is stored in the ROM of the microcomputer constituting the above. This combination is stored according to the rotation direction of the electric motor 11.

As described above, when the contact point a of the switching means 16 is connected, the control means 17 controls the switching means 1 so that the electric motor 11 operates by full-wave drive with 120-degree conduction.
To 6 are turned on and off. However, this is merely an example, and sine wave driving or full-wave driving with 150-degree conduction may be used.

FIG. 4 shows the switching means 1 to 6 and the Hall ICs 19 to 2 when the contact b of the switching means 16 is connected.
1 shows operation waveforms of currents flowing through the stator windings 12u, 12v, and 12w. The inverter device according to the present embodiment includes:
The electric motor 11 is driven by a half-wave of 120-degree conduction. (A) shows the output waveform of the Hall IC 19, (b) shows the output waveform of the Hall IC 20, and (c) shows the output waveform of the Hall IC 21. (D) is the on / off state of the switching means 1,
(E) is an on / off state of the switching means 2, (f) is an on / off state of the switching means 3, (g) is an on / off state of the switching means 4, (h) is an on / off state of the switching means 5, and (i) is a switching means. 6 shows an on / off state. (J) is the current waveform of the stator winding 12u, (k) is the current waveform of the stator winding 12v, (l)
Shows the current waveform of the stator winding 12w. As in FIG. 3, the current waveforms (j), (k), and (l) have the direction of the arrow in FIG. 1 positive. As shown in FIG. 4, since all of the switching means 1 to 3 are in the off state, no current flows in the positive direction of the stator windings 12u, 12v, and 12w. Each of the switching means 4 to 6 is turned on for a period of 120 electrical degrees. The ROMs of the microcomputer constituting the control means 17 include Hall ICs 19 to 21.
Of the switching means 4 to 6 corresponding to the logic of the output signal is stored. This combination is stored according to the rotation direction of the electric motor 11. The driving method of the electric motor 11 is an example, and may be, for example, a sine-wave half-wave drive or a half-wave drive with 150-degree conduction.

As described above, when the switching means 16 connects the DC power supply 15 to the neutral points of the stator windings 12u, 12v, and 12w, the switching means 1 to 3 are all turned off. 6, the regenerative current generated at the time of turning off only flows through the reverse connection diodes of the switching means 1 to 3, thereby realizing an inverter device that generates less heat. Further, since power for turning on the switching means 1 to 3 is not required, power saving of the control means 17 can be realized. FIG. 4 shows a third embodiment of the present invention.

(Embodiment 2) FIG. 5 shows the switching means 1 to 6 and the hole I when the contact b of the switching means 16 is connected.
Another example of operation waveforms of currents flowing through C19 to C21 and stator windings 12u, 12v, and 12w is shown. Other configurations are the same as those of the inverter device shown in FIGS. Referring to FIG. (A) shows the output waveform of the Hall IC 19, (b) shows the output waveform of the Hall IC 20, and (c) shows the output waveform of the Hall IC 21. (D) is the on / off state of the switching means 1,
(E) is an on / off state of the switching means 2, (f) is an on / off state of the switching means 3, (g) is an on / off state of the switching means 4, (h) is an on / off state of the switching means 5, and (i) is a switching means. 6 shows an on / off state. (J) is the current waveform of the stator winding 12u, (k) is the current waveform of the stator winding 12v, (l)
Shows the current waveform of the stator winding 12w. (J)
In the current waveforms (k) and (l), the direction of the arrow in FIG. As shown in FIG. 5, all of the switching means 1 to 6 are turned on during a period of 120 electrical degrees. The ROM of the microcomputer constituting the control means 17 includes Hall ICs 19 to 21.
Of the switching means 1 to 6 corresponding to the logic of the output signal is stored. This combination is stored according to the rotation direction of the electric motor 11. In this embodiment, as shown in FIG. 5, while the electric motor 11 is driven by the switching means 4 to 6 at a half-wave of 120-degree conduction, the switching means 1 to 3 are simultaneously turned on / off based on a combination preset in the ROM. By doing so, the regenerative current generated when the switching means 4 to 6 are turned off flows to another stator winding through the switching means 1 to 3, so that the capacitor 14 can be prevented from being excessively charged by the regenerative current. . As shown in FIG. 5, the on / off control of the switching units 1 to 6 in the present embodiment is the same as the on / off control of the switching units 1 to 6 when the DC power supply 15 and the capacitor 14 shown in FIG. Is the same. Therefore, it is not necessary to store the on / off states of the switching means 1 to 6 corresponding to the respective connection states of the contact points a and b of the switching means 16, and the ROM in the microcomputer can be saved. However, the driving method of the electric motor 11 is an example, and for example, at least one of the high-potential-side switching means 1 to 3 has an electrical angle of 360
It may be turned on once within a certain time, or may be turned on only once during operation of the electric motor 11.
Further, the switching means 1 to 3 on the high potential side may be subjected to pulse width modulation (PWM). FIG. 5 shows a fourth embodiment of the present invention.

(Embodiment 3) FIG. 6 shows a flowchart when the electric motor 11 of the inverter device according to a fifth embodiment of the present invention is driven. Note that the configuration of the inverter device is the same as that of FIG. 1 and is omitted here.

The flowchart of the inverter device shown in FIG. 6 will be described. When the operation of the electric motor 11 is started, in step 31, the target speed of the electric motor 11 becomes Ns.
Set. The target speed Ns may be set by a user of the inverter device, or may be set in advance in a sequence of devices in which the inverter device is incorporated. When the target speed Ns is set, the target speed Ns is compared with the predetermined speed Nref in Step 32. If the target speed Ns is equal to or lower than the predetermined speed Nref, in Step 33, the contact a of the switching means 16 and the DC power supply 15 Connect the terminal on the high potential side. Thereby, the stator windings 12u, 1
The neutral points of 2v and 12w are not connected. In step 34, the control means 17 controls the Hall IC 19 as shown in FIG.
On / off control of the switching means 1 to 6 corresponding to the combination of the output logics of 〜 to ２１, drives the electric motor 11 to the target speed Ns with three-phase full waves. If the target speed Ns exceeds the predetermined speed Nref in step 32, the contact b of the switching means 16 and the DC power supply 15 are connected in step 35. That is, the DC power supply 15 and the stator winding 12
The neutral points of u, 12v, and 12w are connected. This allows
The power supply to the motor 11 is performed without passing through the high-potential side switching means 1 to 3. Thereafter, in step 36, as shown in FIG.
, The electric motor 11 is driven by three-phase half-wave. Although the method of setting the predetermined speed Nref is not particularly limited, in the present embodiment, the speed-torque characteristic (a) when the contact a of the switching means 16 shown in FIG. 2 is connected.
And the crossing speed of the speed-torque characteristics (b) when the contact point b of the switching means 16 is connected is set to the predetermined speed Nref. In this embodiment, the speed of the electric motor 11 is detected by the control means 17 detecting the period of the output signal of the Hall IC 19. More specifically, the speed of the electric motor 11 is detected by detecting the high period of the Hall IC 19 by a counter provided in the microcomputer constituting the control means 17, and the control means 17 is controlled so as to reach the target speed. The duty ratio of the switching means 4 to 6 on the low potential side during the ON period is subjected to pulse width modulation (PWM).

As described above, the target speed Ns of the motor 11
Is less than or equal to the predetermined speed Nref, the contact point a of the switching means 16 is connected to drive the electric motor 11 with three-phase full-wave. When the target speed Ns exceeds the predetermined speed Nref, the switching means 1
By connecting the contact b of No. 6 and driving the electric motor 11 with a three-phase half-wave, the electric motor 11 can be driven by a more efficient driving method depending on the speed of the electric motor 11. FIG. 6 shows a fifth embodiment of the present invention.

(Embodiment 4) FIG. 7 is a circuit diagram of a main part of an inverter device according to Embodiment 4 of the present invention. The DC power supply 1 and the low potential side terminal of the capacitor 14 are directly connected, and the low potential side terminal of the DC power supply 15, the low potential side terminal of the capacitor 14, and the neutral point of the stator windings 12u, 12v, and 12w. Switching means 41 is provided between them. The switching means 41 is constituted by a relay, and this relay is connected to the contact b by coil excitation to connect the stator windings 12u, 12u.
v, 12w and the low-potential side terminal of the DC power supply 15 are connected to each other, and the capacitor 1 is connected to the contact a by non-excitation.
4 and the low potential side terminals of the DC power supply 15 are connected.

The control means 42 comprises Hall ICs 19, 20, 2
Switching means 1 according to the combination of the output logics 1
6 and the on / off control of the relay as the switching means 41 is also performed. Other configurations are the same as those of the inverter device shown in FIG.
Here, it is omitted.

The operation of the inverter shown in FIG. 7 will be described. When the contact point a of the switching means 41 is connected, the control means 42 controls the Hall IC 19 as shown in FIG.
On / off control of the switching means 1 to 6 in accordance with the combination of the output logics of .about.21. Thereby, the electric motor 11 is driven by three-phase full waves.

When the contact b of the switching means 41 is connected, the DC power supply 15 and the stator windings 12u, 12v, 12w
Will be connected. The control means 42 includes the low-potential-side switching means 4 to 4 provided with the switching means 41.
6 are turned off, and the switching means 1 to 3 are turned on / off in accordance with a combination of output logics of the Hall ICs 19 to 21. Thus, the electric motor 11 is driven by three-phase half-wave.

As described above, also in the inverter device of the present embodiment, the low potential side output terminal of the DC power supply 15 is switched to the low potential side of the capacitor 14 by switching the connection of the contact a and the contact b constituting the switching means 41. Side terminals or the neutral points of the stator windings 12u, 12v, 12w to switch the maximum applied voltage to the stator windings 12u, 12v, 12w, and to change the electric motor 11 to a three-phase full-wave or half-wave. , The operating area of the electric motor 11 can be changed. Note that the speed of the electric motor 11 in the inverter device of FIG.
The torque characteristics are the same as in FIG. FIG. 7 shows an embodiment of the first, second and third aspects of the present invention.

(Embodiment 5) FIG. 8 shows an inverter device according to Embodiment 5 of the present invention.

Switching means 51, 52, 53, 54
Are each composed of a parallel circuit of an IGBT and a reverse-connected diode capable of supporting high-frequency switching and large current capacity. However, the present invention is not limited to this.
A transistor or MOSFET may be used instead of T.

The series circuit 55 is composed of a high-potential side switching means 51 and a low-potential side switching means 53 connected in series. The series circuit 56 is configured by connecting the switching means 52 on the high potential side and the switching means 54 on the low potential side in series.

The inverter circuit 57 includes series circuits 55 and 56
Are connected in parallel. That is, the inverter circuit 57 is configured such that the switching means 51, 52, 53, 54 are full bridges.

The electric motor 58 is constituted by a rotor 59 provided with four-pole permanent magnets and a stator 60 in which stator windings 60a and 60b are connected in series. More specifically, although not specifically shown, the stator core 60 is provided with two slots, and the stator winding 60
a and 60b are wound around each slot.

The switching means 61 is composed of a relay, and is provided between the high-potential output terminal of the DC power supply 15, the high-potential terminal of the capacitor 14, and the connection between the stator windings 60a and 60b. This relay connects the DC power supply 15 to the connection portion between the stator windings 60a and 60b by coil excitation and connects the connection between the stator windings 60a and 60b, and connects the capacitor 14 and the DC power supply 15 by non-excitation to connect the contact a.

The control means 62 is constituted by a microcomputer, a plurality of logic circuits, and the like. The control means 62 controls the switching means 51 to 54 on and off and controls the connection of the switching means 61 by the output logic of the Hall IC 63 as the position detecting means.

The operation of the inverter device shown in FIG. 8 will be described. When the contact “a” of the switching means 61 is connected, the output terminal on the high potential side of the DC power supply 15 is connected to the terminal on the high potential side of the capacitor 14. The control means 62 controls on / off of the switching means 51 to 54 according to the output logic of the Hall IC 63 and the rotation direction of the electric motor 58,
The electric motor 58 is driven by a single-phase full wave. When the contact b of the switching means 61 is connected, the output terminal on the high potential side of the DC power supply 15 is connected to the connection between the stator windings 60a and 60b. The control means 62 is the switching means 5 on the high potential side.
1 and 52 are kept off, and the Hall IC 63
The switching means 53 and 54 are turned on and off in accordance with the output logic of.

As described above, also in the inverter device of the present embodiment, the connection of the output terminal on the high potential side of the DC power supply 15 using the switching means 61 is used to connect the terminal on the high potential side of the capacitor 14 and the stator winding 60a. , 60b,
Since the maximum applied voltage to the stator windings 60a and 60b is changed and the driving method of the electric motor 58 is changed to full-wave driving and half-wave driving, the operation area of the electric motor 58 can be changed. The inverter device shown in FIG. 8 corresponds to an embodiment of the present invention.

As described above, the connection of the output terminal of the DC power supply is switched to the connection of the stator winding and the input terminal of the inverter circuit by the switching means, so that the maximum voltage applied to the stator winding can be changed. At the same time, since the driving method of the motor is switched between full-wave driving and half-wave driving, in a DC brushless motor having a permanent magnet in the rotor as in this embodiment, the maximum value of the induced electromotive force generated in the stator winding is increased. Can increase the maximum speed. Although not shown in the present embodiment, the configuration of the electric motor may be an induction motor or a switch reluctance motor. Also in this case, the maximum applied voltage to the winding is switched by turning on and off the switching means, and the driving method of the motor is switched to full-wave driving or half-wave driving. Can be increased. Therefore, the torque output at high speed can be increased, and the operating region of the electric motor can be expanded.

[0065]

As described above, according to the first aspect of the present invention, an inverter circuit provided with a plurality of series circuits each including two switching means and a plurality of stators connected to the output of the inverter circuit are provided. An electric motor having a winding, a capacitor connected to an input terminal of the inverter circuit,
DC power supply, switching means connected to one end of the output of the DC power supply, and control means for controlling the switching means, wherein the switching means connects between one end of the output of the DC power supply and one end of the capacitor And the connection between one end of the output of the DC power supply and the connection between the stator windings is switched, so that the maximum value of the voltage applied to the stator windings is approximately doubled by the switching means. When one end of the output of the DC power supply is connected to the connection between the stator windings by the switching means, one end of the output of the DC power supply is switched to the output of the capacitor by the switching means. As compared with a case where the motor is connected to one end, electric power of up to about four times can be supplied to each of the stator windings, and the operation area of the electric motor can be changed.

According to a second aspect of the present invention, in the first aspect of the present invention, the electric motor has a permanent magnet in a rotor, and the motor has a permanent magnet relative to the stator winding. And a control unit controls the switching unit in accordance with the output of the position detection unit, so that the maximum value of the voltage applied to the stator winding is controlled by the switching unit. When one end of the DC power supply is connected to the connection between the stator windings by the switching means, one end of the output of the DC power supply is connected to the capacitor by the switching means. The motor can be driven to a speed at which the induced electromotive force generated in the stator winding is about twice as compared with the case where the motor is connected to one end of the output. Since the induced electromotive force is proportional to the speed of the electric motor, the speed of the electric motor can be approximately doubled at the maximum. Further, by providing a permanent magnet to the rotor, an inverter device for driving a highly efficient electric motor can be realized.

According to a third aspect of the present invention, in the first aspect of the present invention, the switching means connects the plurality of stator windings constituting the DC motor to the motor. When the unit is connected, the control means turns off all the switching means on the potential side to which the switching means is connected, so that the regenerative current generated when the switching means is turned off can be reduced, and the loss of the switching means can be reduced. Can be suppressed. Further, since only one switching unit is turned on, the driving power of the switching unit can be suppressed.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the switching means connects the DC power supply to the plurality of stator windings constituting the motor. When the unit is connected, the control unit turns on at least one of the switching units on the potential side connected to the switching unit at least once, and occurs when the switching unit is turned off. The regenerative current flows to another stator winding through this switching means when the switching means on the potential side opposite to the turned off switching means is turned on, so that the capacitor can be prevented from being excessively charged. Therefore,
An inverter device with less failure due to overvoltage can be realized.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, when the target speed of the electric motor is within a predetermined speed, the switching means includes a DC power supply and a capacitor. One end of the DC power supply is connected to a connection between a plurality of stator windings constituting the motor when the speed exceeds a predetermined speed, so that when the target speed of the motor is low, When the motor is driven by full-wave and the target speed of the motor is high, the motor is driven by half-wave, so that the motor can be driven efficiently under connection conditions suitable for the target speed of the motor.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a main part of an inverter device according to a first embodiment of the present invention.

FIG. 2 is a speed-torque characteristic diagram of a motor of the inverter device.

FIG. 3 is an operation waveform diagram of a main part when a contact a of a switching means 16 of the inverter device is connected.

FIG. 4 is an operation waveform diagram of a main part when the contact point b of the switching means 16 of the inverter device is connected.

FIG. 5 is an operation waveform diagram of a main part when the contact point b of the switching means 16 of the inverter device according to the second embodiment of the present invention is connected.

FIG. 6 is a drive control flowchart of a motor of the inverter device.

FIG. 7 is a circuit diagram of a main part of an inverter device according to a fourth embodiment of the present invention.

FIG. 8 is a circuit diagram of a main part of an inverter device according to a fifth embodiment of the present invention.

FIG. 9 is a circuit diagram of a main part of a conventional inverter device.

[Explanation of symbols]

 1, 2, 3, 4, 5, 6 Switching means 7, 8, 9 Series circuit 10 Inverter circuit 11 Motor 12 Stator 12u, 12v, 12w Stator winding 13 Rotor 14 Capacitor 15 DC power supply 16 Switching means 17 Control Means 18 Position detection means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasudo Kobayashi 1006 Kazuma Kazuma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. 5H007 BB06 CA01 CB05 CC01 DB01 DB12 DC07 EA02 5H576 DD07 EE11 HA02 HB01 JJ03 LL10 LL41

Claims (5)

[Claims] An electric motor having an inverter circuit provided with a plurality of series circuits including two switching means, a plurality of stator windings connected to an output of the inverter circuit, and a capacitor connected to an input terminal of the inverter circuit. ,
DC power supply, switching means connected to one end of the output of the DC power supply, and control means for controlling the switching means, wherein the switching means connects between one end of the output of the DC power supply and one end of the capacitor And an inverter device for switching a connection between one end of an output of the DC power supply and a connection portion between the stator windings. 2. An electric motor having a permanent magnet on a rotor, and a position detecting means for detecting a relative position of the permanent magnet with respect to the stator winding, and a control means for outputting an output of the position detecting means. The inverter device according to claim 1, wherein the switching device is controlled in accordance with the switching device. 3. When a connecting portion between a plurality of stator windings constituting a DC power supply and an electric motor is connected by the switching means,
3. The inverter device according to claim 1, wherein the control unit turns off all switching units on the potential side to which the switching unit is connected. 4. When a connecting portion between a plurality of stator windings constituting a DC motor and an electric motor is connected by a switching means,
3. The inverter device according to claim 1, wherein the control means turns on at least one of the switching means on the potential side connected to the switching means at least once. 5. The switching means connects a DC power supply to one end of a capacitor when a target speed of the motor is within a predetermined speed, and connects the plurality of stator windings constituting the motor with a connection portion when the target speed exceeds the predetermined speed. The inverter device according to claim 1, wherein one end of the DC power supply is connected.