JP3510534B2 - Motor control device and control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device and a control method, and more particularly to phase control of a permanent magnet embedded motor that uses reluctance torque instead of magnet torque by embedding a permanent magnet inside a rotor. The present invention relates to such a motor control device and a control method.

[0002]

2. Description of the Related Art In recent years, environmental problems have become a social topic, and energy saving has become an important concern. Particularly, in the motor field, from the viewpoint of energy saving, there is a strong demand for a small size, high efficiency, and high output motor. Under such circumstances, a motor having a structure different from the conventional one has appeared.

FIG. 10 is a diagram showing a typical structure of a conventional motor. In FIG. 10, a permanent magnet 122 is arranged on the outer peripheral surface of a rotor 121 formed of laminated steel plates to prevent non-magnetic SU from scattering during rotation.
The structure is fixed by the S pipe 123. This motor is an SPM (Surface Permanent Magnet) motor that uses a Fleming torque that complies with the Fleming's law by a magnetic field generated by the permanent magnet 122 and a coil current (not shown), and is an excellent motor in terms of mass productivity.

However, an IPM (Interior Peer) which uses a reluctance torque in addition to the fleming torque by embedding a permanent magnet inside the rotor in order to further improve the efficiency.
rmanent Magnet) motors are attracting attention.

FIG. 11 is a diagram showing an example of the structure of an IPM motor. In FIG. 11, the IPM motor constitutes a rotor by embedding a permanent magnet 132 inside a rotor core 131 made of an iron core of a high magnetic permeability material or a laminated silicon steel plate. FIG. 11 shows a 4-pole motor,
Pole (1/2 model in FIG. 11) permanent magnets 132 are arranged so that the N and S poles alternate along the circumferential direction. A stator 135 having teeth 136 is provided on the outer circumference of the rotor core.

With such a structure, the direction d connecting the center of the permanent magnet 132 and the center of the rotor 131.
Inductance Ld in the axial direction and inductance L in the q-axis direction, which is a direction rotated by an electrical angle of 90 ° with respect to the d-axis
A difference occurs in q, and reluctance torque is generated in addition to the Fleming torque by the permanent magnet 132. According to “Rotating Machine Utilizing Reluctance Torque”, Nobuyuki Matsui et al., T. EEE Japan Vol. 114-D, No. 9, 1994), this relationship is expressed by equation (1).

T = Pn × φa × iq + Pn × 1/2 × (Ld−Lq) × id × iq (1) where Pn: number of pole pairs φa: interlinkage magnetic flux Ld: d-axis inductance Lq: q-axis inductance id: d-axis current iq: q-axis current In the SPM motor shown in FIG. 10, since the magnetic permeability of the permanent magnet is almost equal to that of air, both inductances L of the formula (1) are
d and Lq have almost the same value, and the reluctance torque of the second term of the equation (1) does not occur. However, in the IPM motor shown in FIG. 11, the inductance in the d-axis direction is the direction in which the magnetic flux of the permanent magnet is generated, and the flow of the magnetic flux in the d-axis direction passes through the permanent magnet whose magnetic permeability is almost the same as that of air. The resistance increases and the inductance Ld in the d-axis direction decreases.

On the other hand, since the inductance in the q-axis direction passes through the gap of the permanent magnet, the magnetic resistance decreases and the inductance Lq in the q-axis direction increases. Therefore, d
A difference occurs between the inductance Ld in the axial direction and the inductance Lq in the q-axis direction, and the d-axis current Id is caused to flow, whereby the reluctance torque of the second term of the equation (1) is generated.

From the viewpoint of the magnetic flux vector, from the viewpoint of the magnetic flux vector, the Fleming torque Tm is generated by multiplying the magnetic flux φa by the electric current Iq in the direction perpendicular to the electric flux. Similarly, the reluctance torque Tr is generated by the inductance and the electric current. It is generated by multiplying the magnetic fluxes Ld · Id and Lq · Iq by the electric currents Id and Iq which are electrically orthogonal to each other. The total torque Tt is the sum of these two torques.

By the way, the total torque changes depending on the input current phase β. Here, the current phase β represents the phase of the motor current with respect to the positional relationship between the permanent magnet and the coil in terms of electrical angle. This is taken into consideration in the equation (2) in the equation (1).

Tt = Pn × φa × ia × cos β + Pn × 1/2 × (Ld−Lq) × ia ² × sin 2β (2) where Pn: number of pole pairs φa: interlinkage magnetic flux Ld: d-axis inductance Lq: q-axis inductance id: d-axis current iq: q-axis current β: current phase ia: magnitude of current vector In FIG. 12, the Fleming torque Tm and the reluctance torque Tr when the current phase β is changed and both are added. The relationship of total torque Tt is shown. At this time, the center of the permanent magnet is the coil center (for example, the U-phase coil center).
The current phase of the U phase when positioned at 90 ° is 90 °.
The Fleming torque Tm shows the maximum value at the current phase of 90 °, becomes smaller as the current phase advances, and becomes 0 at 180 °.
Becomes

On the contrary, the reluctance torque Tr has a characteristic that it exhibits the maximum value at the current phase of 135 °. Therefore, the total torque Tt obtained by adding the two changes depending on each torque ratio, but as shown by the solid line in FIG.
The current phase has a maximum value near 115 °. Therefore, the IPM motor that effectively uses the reluctance torque is an SP that uses only the fleming torque.
High torque can be output from the M motor with the same current.

The current drive method is also important as a factor that determines the magnitude of torque. FIG. 13 is a waveform diagram showing an example of 120 ° rectangular wave driving which is a conventional current driving method. In FIG. 13, (a), (b) and (c) are current waveforms of the U phase, V phase and W phase, respectively. FIG.
As shown in, the current drive method is a method in which current is applied to two of the three phases (U, V, W), and the inverters are connected at 120 ° intervals to control the inverter, and the current drive method is used. As can be seen, although there is a rest period, the rotor rotation is controlled by detecting the induced voltage generated in the stator coil due to the rotation of the rotor magnet during that period.

As described above, in the IPM motor utilizing reluctance torque, it is important to control the energization timing in order to obtain the maximum torque. Conventionally, the rotor phase detection by the induced voltage is used as the rotor phase detection method.
There was only a 20 ° rectangular wave driving method. However, the 12
The 0 ° rectangular wave driving method has a problem in terms of motor efficiency, vibration, and noise because there is a pause period for detecting the induced voltage.

Therefore, the international publication number: W095 / 273
28 has been proposed. According to this method, in a motor having a permanent magnet embedded therein, a conduction width is set to an electrical angle of 180 °, and further, a first neutral point potential of a motor coil and a bridge circuit electrically parallel to the coil. The method for detecting the magnetic pole position based on the difference from the second neutral point potential of

FIG. 14 is a block diagram showing the structure of a brushless DC motor drive controller for energizing 120 °. In FIG. 14, three pairs of switching transistors 212u, 212 are provided between the terminals of the DC power supply 211.
v and 212w are connected in series to form an inverter, and the connection point voltage between the switching transistors of each pair is applied to the Y-connected stator windings 213u, 213v, and 213w of each phase of the brushless DC motor, respectively. There is. Then, the resistors 214u, 214v, and 21 having the Y connection of the connection point voltage between the switching transistors of each pair are connected.
It is also applied to 4w.

Further, here, the stator windings 213u, 21
Wiring 213 that gives neutral point 213d of 3v, 213w
e, resistors 214u, 214v, 214w, and a wiring 214e for providing a neutral point. Furthermore, the neutral point 213d
Is supplied to the inverting input terminal of the amplifier 215 via the resistor 215a, and the voltage at the neutral point 214d of the Y-connected resistor is supplied to the non-inverting input terminal of the amplifier 215 as it is. Then, by connecting the resistor 215b between the output terminal and the inverting input terminal of the amplifier 215, it operates as a differential amplifier.

Here, the stator windings 213u, 213v,
The voltage En0 at the neutral point 213d of 213w is the sum of the inverter output waveform and the 3nth harmonic component (n is an integer) included in the motor induced voltage waveform. On the other hand, the neutral point 214 of the resistors 214u, 214v, and 214w whose connection point voltage is Y-connected.
The voltage of d is only the inverter output waveform, and 3n included in the motor induced voltage waveform by obtaining the difference between the two voltages.
The next harmonic component can be extracted. As described above, the detection of the motor induced voltage waveform, that is, the rotor position detection can be achieved without using the magnetic pole position sensor.

[0019]

However, the above-mentioned conventional example also has the following drawbacks. That is, in order to operate the magnet-embedded IPM motor at the highest efficiency, there is an optimum energization phase lead angle of the current, and in order to set the optimum energization phase lead angle, the phase detection of the rotor relative to the stator is important. . Therefore, international publication number: WO95 / 27
In 328, the wiring which gives a neutral point from the motor coil connection and the resistance connection 14 u, v, w which is 180 ° sine wave energization
The wiring that gives the neutral point and the external circuit such as the differential amplifier and the auxiliary circuit are provided to enable the rotor phase detection, but the wiring, the discrimination detection circuit, the resistor and other parts are required for the detection. It causes the number of parts and cost increase.
In particular, the wiring that provides the neutral point 13d from the motor coil connection has a problem that the motor structure and the terminal structure need to be changed and cannot be applied to the conventional motor.

Furthermore, a problem with the conventional method is that it is difficult to control. This is because a phase difference occurs between the applied voltage and the coil terminal current due to the influence of the magnet induced voltage and the reluctance torque generating magnetic flux in 180 ° sine wave energization, and the efficiency characteristic of the applied voltage with respect to the energized phase is steep as compared with 120 ° energization. Therefore, there is a problem that the efficiency greatly changes unless accurate phase control is performed.

Therefore, a main object of the present invention is to provide a motor control device and a control method which can reduce the number of parts to reduce the cost and control is stable.

[0022]

A first aspect of the present invention is a motor control device in which a magnet is embedded in a rotor and the rotor is rotated by utilizing reluctance torque, and a current flowing through a coil of the motor. Detecting means for outputting the current phase information, the applied voltage phase information setting means for setting the phase information of the coil applied voltage applied to the coil, the current phase information output from the current detecting means and the application. Comparison means for comparing the applied voltage phase information set by the voltage phase information setting means to detect a phase difference, phase difference reference value storage means for storing a desired phase difference reference value in advance, and comparison means for detecting the phase difference. And a drive means for driving the motor so that the phase difference information of the difference between the phase difference and the phase difference reference value stored in the phase difference reference value storage means becomes a desired value.

In the second aspect of the invention, the phase information setting means of the first aspect of the invention is a rotation speed setting means for setting the rotation speed of the motor, and a sine wave table for storing sine wave data corresponding to the rotation speed in advance. Sine wave data creating means for reading the corresponding sine wave data from the sine wave table based on the set rotation speed and outputting phase information of the coil applied voltage, and the driving means includes a position detected by the comparing means. A pulse width modulation signal for each phase is generated based on the phase difference information of the difference between the phase difference and the phase difference reference value stored in the phase difference reference value storage means and the sine wave data output from the sine wave data creating means. A pulse width modulated signal creating means to be created and a switching element provided for each phase, and a corresponding switch based on the pulse width modulated signal created by the pulse width modulated signal creating means. And an inverter means for switching the device.

In the third aspect of the invention, the phase difference between the coil current of the motor and the phase of the coil applied voltage is zero.

In the fourth aspect of the invention, the energization width of the coil voltage of the motor has an electrical angle of 180 ° and the energization waveform is a sine wave.

A fifth aspect of the present invention is a method of controlling a motor in which a magnet is embedded in the rotor and the rotor rotates by utilizing reluctance torque. The current flowing in a coil of the motor is detected to detect a current phase. Outputs information and sets the phase information of the coil applied voltage applied to the coil, detects the phase difference by comparing the output current phase information and the set applied voltage phase information, and detects the detected phase difference. The motor is driven so that the phase difference information of the difference from the phase difference reference value stored in advance has a desired value.

[0027]

FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, the IPM motor 1 uses the fleming torque and the reluctance torque in combination to increase the torque, as described in the related art. IPM
The motor 1 is driven by an inverter circuit 2, and the inverter circuit 2 is supplied with DC power from a converter circuit 3 that converts an AC power supply 4 into DC. Current sensor 17
Detects the motor current flowing in a specific phase among the motor coils U, V, W and supplies the detected current to the current detection unit 5,
Outputs the current phase information 15.

A microcomputer (hereinafter, referred to as a microcomputer) 6 includes a phase difference detection unit 7, a target phase difference information storage unit 8, a rotation speed setting unit 9, a sine wave data table 10, a sine wave data creation unit 11, and a PWM. The function as the creation unit 12 is realized by software processing. That is, the phase difference detection unit 7 A / D converts the motor current signal at a predetermined interval and takes in the signal.
The motor drive voltage phase and the motor drive current phase are compared and detected as phase difference information. The target phase difference information storage unit 8 stores target phase difference information in advance. The rotation speed setting unit 9 sets a rotation speed command for the IPM motor 1. The sine wave data table 10 stores a predetermined number of pieces of sine wave data in advance. The sine wave data creation unit 11 outputs the sine wave data 13 corresponding to each phase of the motor coil terminals U, V, and W from the sine wave data table 10 to the PWM creation unit 12 according to the rotation speed command and the passage of time, and the U phase U-phase motor drive voltage phase information 14 from the sine wave data
Is output to the phase difference detection unit 7. The phase difference information output from the phase difference detection unit 7 and the phase difference information output from the target phase difference information storage unit 8 are added by the adder 18 and the gain is adjusted.
Given to 2.

The current detector 5 may be a so-called current sensor composed of a coil and a Hall element, or may be a current transformer. Further, the sine wave data may be created by calculation instead of the sine wave data table 10. Further, although the target phase difference information storage unit 8 to the PWM creation unit 12 are configured by the microcomputer 6 in FIG. 1, the present invention is not limited to this and may be configured by a hardware circuit.

The program content for software processing by the microcomputer 6 may be stored in a memory such as a ROM at the time of shipment from the factory, or may be stored in a rewritable memory such as a flash ROM. It is possible to update and modify the contents at any time.

Next, a specific operation of the embodiment of the present invention will be described. First, the AC voltage supplied from the AC power source 4 is converted into a DC voltage by the AC-DC converter 3 and applied to the inverter circuit 2. Inverter circuit 2 IGBT (Insulated Gate Bipolar Transis)
Each drive element such as tor) is controlled by the PWM creating unit 12 and is switched at a desired duty to generate the IPM.
The motor 1 is driven by being applied to each phase.

Further, the current detector 5 is a current sensor for detecting a certain one-phase current (W phase in this case) of the IPM motor 1. T. The output from (Current Transducer) or the like is taken into the microcomputer 6, and the current phase information 15 is output. After performing a predetermined process, the microcomputer 6 outputs a control signal to the inverter circuit 2. Each operation of the microcomputer 6 will be described below. The sine wave data creating unit 11 outputs the sine wave data 13 based on the information from the sine wave data table 10 and the rotation speed setting unit 9. The sine wave data table 10 stores a data string that becomes a sine wave signal when continuously A / D-outputted, and the rotation speed setting unit 9 uses the IPM.
The target rotation speed information of the motor 1 is output.

The sine wave data creating unit 11 selects the sine wave data corresponding to the above speed data from the plurality of data in the sine wave data table 10 based on the speed data information set by the rotation speed setting unit 9. To output. The selection and output of this data are performed every predetermined time (PWM carrier period) determined by the PWM period. The high speed and the low speed are, for example, low speed commands if the sine wave data selected from the sine wave table 10 is such that the data strings in the table are sequentially selected. If it does, it will be a high-speed command.

The output from the sine wave data creating unit 11 is P
It is input to the WM creating unit 12 and is also given to the phase difference detecting unit 7 as voltage phase information 14 indicating the reference phase (0 °) of the sine wave data. The phase difference detection unit 7 detects the phase of the current detected by the current detection unit 5 with reference to the voltage phase information 14 created by the sine wave data creation unit 11, and determines the level of the motor current with respect to the motor applied voltage. Calculate the phase difference.

As a method of detecting this phase difference, for example, the current (current phase information) is sampled a predetermined number of times during the electrical angle of 180 ° of the sine wave data 13, and is sampled during the electrical angle of 0 to 90 °. It is calculated by taking the ratio of the sum of the discrete current values and the sum of the discrete current values sampled in the period of the electrical angle of 90 to 180 °. In other words, by taking the ratio of the area of the current waveform during the electrical angle 0 to 90 ° with respect to the voltage waveform and the area of the current waveform during the electrical angle 90 to 180 °, the current with respect to the voltage waveform is obtained. Detect the waveform phase. The difference between the detected phase difference and the phase difference information created in the target phase difference information storage unit 8 storing the phase information is the adder 1
8 is added and multiplied by a predetermined gain G to obtain voltage data 16
Is input to the PWM creating unit 12. The PWM creation unit 12 multiplies the sine wave data 13 and the voltage data 16 to PWM
The duty of the signal is determined and the PWM signal is distributed to each drive element to output a command signal for switching the drive element. Here, since two control signals are used for each phase, command signals of 3 phases × 2 lines / phase = 6 lines are output.

As described above, the feedback control for detecting the speed command (the cycle of the sine wave data) set on the side of the microcomputer 6 and the phase difference between the voltage / current and controlling the drive voltage (duty) from this is constructed. And the IP
It is possible to drive the M motor 1 at a predetermined rotation speed and at an energization timing that maximizes efficiency.

The principle of motor control of one embodiment of the present invention thus configured will be described with reference to FIGS. 2 and 3.

FIG. 2 shows torque characteristics with respect to the energization characteristics of a general Fleming torque type brushless DC motor. In FIG. 2, the Y-axis 20 shows the torque and the voltage-current phase difference, and the X-axis 21 shows the energizing current phase of the stator coil with respect to the rotor magnet. The phase difference of the energizing current when the center of the stator coil is at the center of the rotor magnet is 0 °.

Characteristic 22 is a torque characteristic with respect to the current phase, characteristic 23 shows the maximum value of torque, and characteristic 24
Represents the phase of the energizing current for obtaining the maximum torque value. It can be seen that the torque decreases as the rotor magnet center moves away from the stator coil center. Further, the characteristic 25 shows the coil applied voltage phase with respect to the coil current phase, that is, the voltage-current phase difference, and the characteristic 26 shows the magnetic flux density characteristic of the magnet.

As shown in FIG. 2, a general brushless D
In the C motor, the maximum torque coincides with the energizing current phase value that maximizes the magnetic flux density. This is because the torque is the product of the magnetic flux and the current, and since the magnet magnetic flux 26 is almost a COS (cosine) curve with 0 ° being the maximum, the torque is also 0 °.
This is because the torque curve 22 has the same characteristic (curve) as the magnetic flux density characteristic 26.

Furthermore, when a sinusoidal voltage is applied, the magnetic flux of the magnet, that is, the induced voltage is also sinusoidal. Therefore, the coil applied current represented by the difference between the two has a certain phase difference different from the applied voltage phase. It is represented by a sinusoidal current. The coil applied voltage phase 25 represents the difference between the applied voltage phase and the current phase with respect to the applied current phase. It is generally expressed as a power factor by taking the cosine of the phase difference, and it is desirable that the power factor is "1", that is, the phase difference is "0".

As shown in FIG. 2, in the conventional DC motor using the magnet torque, the peak of the torque curve 23 and the zero point of the phase difference substantially coincide with each other. Maximum efficiency and torque can be obtained by controlling.

FIG. 3 shows the characteristics of the IPM motor 1 which also uses the reluctance torque described above. In FIG. 3, Y-axis 3
0 indicates the torque and the voltage-current phase difference, and the X-axis 31 indicates the phase of the current flowing through the stator coil with respect to the rotor magnet. The magnet torque 32 is for the energized current phase, the reluctance torque 33 is for the energized current phase, and the sum of the two is shown as a total torque characteristic 34. Furthermore, the maximum value of total torque is 35,
The optimum energization current phase 36 for obtaining the maximum torque value, the voltage-current phase difference 37, D with respect to the energization current phase of the IPM motor 1
A voltage-current phase difference 38 and a magnet magnetic flux density characteristic 39 with respect to the energizing phase of the C motor are shown.

IP using reluctance torque together
As a feature of the M motor 1, the total torque is represented by the sum of the Fleming torque and the reluctance torque, and its peak 3
5 is a large point as compared with the peak 31 (23 in FIG. 2) of only the Fleming torque, and there is the optimum energization current phase 36 for obtaining the maximum value.

On the other hand, it has been found that the voltage-current phase characteristic (straight line 37) of the IPM motor 1 deviates from the conventional characteristic 38 due to the influence of the change in magnetic resistance inside the rotor, and zero crosses near the optimum energizing current phase 36. Therefore, IP
In the M motor 1, the energizing current phase is not controlled to be the optimum energizing current phase 36 of the related art, but the voltage is controlled so that the voltage-current phase difference becomes zero.
Maximum torque and maximum efficiency can be obtained.

In the above description, the motor applied voltage is controlled so that the phase difference between the motor current and the motor applied voltage becomes zero. However, it is desirable that the motor current and the motor current be controlled according to the number of revolutions or the load torque. To obtain the maximum torque and maximum efficiency more accurately by controlling the motor applied voltage so that the applied voltage phase difference (hereinafter referred to as voltage-current phase difference, if necessary) is a non-zero desired value. You can

More specifically, in FIG. 3, when the current phase is the maximum current to give the maximum torque 35, the voltage-current phase difference is exactly 0 due to the fluctuation of the rotation speed or the load.
Does not mean Conversely, even in such a case the voltage −
If control is performed such that the current phase difference becomes 0, the torque at that time becomes slightly smaller than the maximum torque. Therefore, for the purpose of accurately obtaining the maximum torque and the maximum efficiency of the IPM motor to be controlled, the motor applied voltage is controlled so that the desired voltage-current phase difference when the maximum torque 35 is given is obtained. do it.

Next, the effect of motor control will be described based on experimental results. FIG. 4 shows the results of an experiment in which the motor efficiency characteristic with respect to the voltage-current phase difference was measured with the IPM motor fixed at an arbitrary rotation speed and load torque. In FIG. 4, the horizontal axis represents the phase difference between the motor current and the motor applied voltage, and the vertical axis represents the efficiency. The characteristic 41 shows the efficiency characteristic when the output (W), which is the product of the rotation speed and the torque, is 400 (W).
2 shows the output characteristic at 200 (W).

As shown in FIG. 4, the motor efficiency characteristic with respect to the voltage-current phase difference shows the same tendency as the motor efficiency characteristic with respect to the conventional energization phase. That is, the energization timing in the prior art is set to the optimum energization current phase that maximizes the efficiency, but in one embodiment of the present invention, if the motor applied voltage is set so as to have a desired voltage-current phase difference. I know it's good.

FIG. 5 shows the experimental results of the voltage-current phase difference with respect to the coil applied voltage value in a state where the rotation speed and the load torque are fixed in the IPM motor. In FIG. 5, the horizontal axis represents the motor coil applied voltage, and the vertical axis represents the voltage −.
A characteristic 51 is a characteristic curve of an applied voltage and a phase difference.

As shown in FIG. 5, it can be seen that the voltage-current phase difference changes by changing the coil applied voltage value. That is, the result of FIG. 5 is that by appropriately controlling only the motor applied voltage without changing the rotation speed and the torque,
It shows that the desired voltage-current phase difference can be set. Therefore, in driving the IPM motor, maximum efficiency control can be performed by controlling the motor applied voltage value so that the voltage-current phase difference becomes the optimum.

FIG. 6 is a diagram showing experimental results of efficiency characteristics with respect to voltage-current phase difference in a state where the rotation speed and load torque are fixed in the IPM motor. An efficiency characteristic of one embodiment of the present invention is shown at 61, and for comparison, an efficiency characteristic when a position sensor is used as a conventional method and control is performed on the basis of an applied voltage is shown at 62. The horizontal axis represents the energization voltage phase in the case of one embodiment of the present invention and the voltage-current phase difference in the case of the conventional technique, and the vertical axis represents the efficiency.

As shown in FIG. 6, the efficiency characteristic of the embodiment of the present invention is gentler than that of the conventional method. As the controlled object, the energized voltage phase and the voltage-current phase difference are different between the conventional technology and this embodiment, but from the viewpoint of control, the phases are both controlled, and therefore the optimum phase for obtaining the highest efficiency is obtained. It can be seen that the setting of 1 has a wider allowable range in this embodiment, and further, even if there is some fluctuation in the voltage-current phase difference, there is little fluctuation in efficiency.

Next, the effect of the motor control according to the embodiment of the present invention will be described focusing on the simulation result. First, the same IPM is used for two types of current waveforms, that is, a 120 ° rectangular wave drive system and a 180 ° sine wave drive system.
We simulated the torque characteristics when the same input power was applied by the motor. The result is shown in FIG. 7. In FIG. 7, the horizontal axis represents the energization voltage phase applied to the motor coil, and the vertical axis represents the torque. A characteristic 71 is a torque characteristic with respect to a conduction voltage phase in the 180 ° sine wave driving method, and a characteristic 72 is a torque characteristic in the 120 ° rectangular wave driving method.

As described above, in each system, there is an energization voltage phase in which the torque has the maximum value, and when comparing the maximum torques of both systems in the optimum energization voltage phase, the 180 ° sine wave drive system is larger. I understand. This is because the distribution of the magnetic flux magnetic field is almost sinusoidal, and the same current flows in the 120 ° rectangular wave during the energization period, so the same current flows even in the section where the magnet magnetic flux is small, but in the 180 ° sinusoidal drive, the magnet magnetic flux is small. If so, the current becomes smaller. As explained in the conventional example, since the motor torque is the product of magnetic flux and current,
The 180 ° sine wave drive uses the current more effectively,
As a result, the torque increases. Therefore, if the required torque is the same, the 180 ° sine wave drive method consumes less current and improves the motor efficiency.

Further, the efficiency characteristic with respect to the conduction voltage phase is steeper in the 180 ° sine wave drive method. Therefore, if the control accuracy of the energization voltage phase is poor, the torque fluctuates, so that accurate energization voltage control is required to control the maximum torque.

Next, the relationship between the coil terminal voltage and the coil current will be described. In FIG. 8, the horizontal axis represents the time axis and the vertical axis represents the voltage and current levels. Characteristic 8 shown in FIG.
1 shows the voltage applied to an arbitrary coil, and the characteristic 82 shows the waveform of the current flowing through the coil after the voltage is applied. Figure 8
In the above, since it is based on the simulation that the motor current is given as an input, the current waveform 82 has a more sinusoidal waveform that is more beautiful than the voltage waveform 81.

As shown in FIG. 8, the motor applied voltage waveform 81
And a motor current waveform 82 has a phase difference. This is caused by the induced voltage of the magnet and the magnetic flux that causes the reluctance torque.

FIG. 9 shows a result of simulating the phase difference between the voltage and the current and the motor efficiency by changing the timing of the voltage applied to the motor. In FIG. 9, a characteristic 91 shows the torque characteristic according to the embodiment of the present invention, the vertical axis shows the torque, and the horizontal axis shows the voltage-current phase difference.

For comparison, the conventional 180
° The torque characteristics of the drive system are shown as 92,
The vertical axis represents the torque and the horizontal axis represents the conduction voltage phase.
As shown in FIG. 9, it was confirmed by simulation that the efficiency characteristic with respect to the energization characteristic is gentler according to the embodiment of the present invention, and thus the control is easier.

It should be understood that the embodiments disclosed this time are exemplifications in all respects, and are not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[0062]

As described above, according to the motor control device of the first to fourth aspects of the present invention, the following effects can be obtained. First, as mentioned above, the magnet-embedded IP
In order to operate the M motor at the highest efficiency, there is an optimum energization phase lead angle of the current, and rotor phase detection is important for setting the optimum energization phase lead angle.

As a first effect, in the conventional example, the wiring which gives 180 ° sinusoidal current and gives a neutral point from the motor coil connection,
The wiring for giving the neutral point to the resistance connections 14u, v, w, an external circuit such as a differential amplifier and an auxiliary circuit are required, and the wiring for providing the neutral point 13d from the motor coil connection is
Although it is necessary to change the motor structure and the terminal structure, the number of parts and the cost are increased. However, according to the present invention, it is possible to apply to a conventional motor without changing the motor structure.

As a second effect, the controllability is excellent. That is, as shown in FIG. 6, the experimental results of the efficiency characteristics with respect to the applied voltage and the voltage-current phase difference in a state where the rotation speed and the load torque are fixed in the IPM motor are shown in FIG.
The efficiency characteristic of this invention is gentler than that of the conventional example. As a result, the setting of the optimum phase angle for obtaining the maximum efficiency has a wider permissible range in the present invention, and there is an effect that the fluctuation of the efficiency is reduced even if there is some fluctuation.

Further, since the current can be effectively used by performing the 180 ° sine wave drive, the maximum torque can be increased and the efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a motor control device according to a phase difference control system of an embodiment of the present invention.

FIG. 2 is a relational diagram of the Fleming torque and the reluctance torque and the energization phase according to the embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a Fleming torque and a reluctance torque and an energization phase according to the embodiment of the present invention.

FIG. 4 is a diagram showing experimental results of a phase difference angle and efficiency in the phase difference control method according to the embodiment of the present invention.

FIG. 5 is a diagram showing experimental results of a conduction phase and a phase difference angle at a constant output according to the embodiment of the present invention.

FIG. 6 is a diagram showing experimental results of efficiency characteristics of the phase difference control method according to the embodiment of the present invention and the conventional method.

FIG. 7 is a diagram showing simulation results of a 180 ° driving method and a 120 ° driving method.

FIG. 8 is a diagram showing a simulation result of a voltage phase and a current phase in a 180 ° drive system.

FIG. 9 is a diagram showing simulation results of efficiency characteristics of the phase difference control method according to the embodiment of the present invention and the conventional method.

FIG. 10 is a sectional view of an SPM motor.

FIG. 11 is a sectional view of the IPM motor.

FIG. 12 is a graph showing the relationship between the fleming torque, reluctance torque, and total torque of the permanent magnet type IPM motor.

FIG. 13 is a waveform diagram showing a configuration of a conventional technique.

FIG. 14 is a diagram showing a conventional 120 ° drive system.

[Explanation of symbols]

1 IPM motor, 2 inverter circuit, 3 converter circuit, 4 AC power supply, 5 current detection unit, 6 microcomputer, 7 phase difference detection unit, 8 target phase difference information storage unit, 9 rotation speed setting unit, 10 sine wave data table , 11 sine wave data creation unit, 12 PWM creation unit,
13 sine wave data, 14 voltage phase information, 15 current phase information, 16 voltage data, 17 current sensor, 18
Adder.

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Claims (5)

(57) [Claims] 1. A magnet is embedded inside the rotor,
A controller for a motor in which the rotor rotates using reluctance torque, wherein current detection means detects current flowing in a coil of the motor and outputs current phase information, phase of a coil applied voltage applied to the coil Applied voltage phase information setting means for setting information, comparing the current phase information output from the current detecting means with the applied voltage phase information set by the applied voltage phase information setting means to detect a phase difference. Comparing means, phase difference reference value storing means for storing a desired phase difference reference value in advance, and difference between the phase difference detected by the comparing means and the phase difference reference value stored in the phase difference reference value storing means 2. A motor control device comprising a drive means for driving the motor so that the phase difference information of 1. becomes a desired value. 2. The phase information setting means, a rotation speed setting means for setting the rotation speed of the motor, a sine wave table for storing in advance sine wave data corresponding to the rotation speed, and the rotation speed setting means. The sine wave data creating means for reading the corresponding sine wave data from the sine wave table and outputting the phase information of the coil applied voltage based on the rotation speed set by Based on the phase difference information of the difference between the phase difference detected by the means and the phase difference reference value stored in the phase difference reference value storage means, and the sine wave data output from the sine wave data creating means. A pulse width modulation signal creating means for creating a pulse width modulation signal for each phase and a switching element provided for each phase are included. 2. The motor control device according to claim 1, further comprising an inverter unit that switches a corresponding switching element based on the pulse width modulated signal. 3. The motor control device according to claim 1, wherein the phase difference between the coil current of the motor and the phase of the coil applied voltage is zero. 4. The motor control device according to claim 1, wherein the energization width of the coil applied voltage of the motor is 180 ° in electrical angle and the energization waveform is a sine wave. 5. A magnet is embedded inside the rotor,
A method of controlling a motor in which the rotor rotates using reluctance torque, comprising: detecting current flowing in a coil of the motor and outputting current phase information; phase information of a coil applied voltage applied to the coil. A step of detecting a phase difference by comparing the output current phase information with the set applied voltage phase information; a step of storing a desired phase difference reference value in advance; And a step of driving the motor so that the phase difference information of the difference between the generated phase difference and the stored phase difference reference value becomes a desired value.