JP3146791B2 - Drive control device for permanent magnet type synchronous motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling the drive of a permanent magnet type synchronous motor mounted on an electric vehicle, and more particularly to a drive control of a permanent magnet type synchronous motor by performing field weakening control. The present invention relates to a control device for performing the control.

[0002]

2. Description of the Related Art A permanent magnet type synchronous motor (hereinafter referred to as a "PM motor" or simply a "motor") has a back electromotive force ωE ₀ (E ₀ : magnetomotive force of a permanent magnet used as a field) due to its operation. (Main magnetic flux), ω: shaft angular velocity of the motor). Therefore, the equivalent circuit per phase of the PM motor can be represented as shown in FIG. In this figure, R is the primary resistance per phase of the PM motor, L is P
The inductance per phase of the M motor, I is the primary current (phase current) of the PM motor, and V is the terminal voltage applied to the motor. When the PM motor is driven using a battery and an inverter, the value obtained by multiplying the battery voltage by the voltage conversion ratio of the inverter is the voltage V.

Further, when the terminal voltage V of this motor is vector-decomposed and expressed using a d-axis voltage _Vd and a q-axis voltage _Vq , the following equations (1) and (2) are obtained. When the vector diagram is drawn based on the equation (1) on the assumption that the primary resistance R is sufficiently small, the result is as shown in FIG. 9B. Where L _d is d-axis inductance and L _q is q
Axis inductance, I _d is d-axis current (field current), I _q
Is a q-axis current (torque current).

[0004]

(Equation 1) V = (V _d ² + V _q ² ) ^1/2 (2) These equations show that vector control of the motor is possible. That is, while controlling the command value of the field current Id to a constant value (for example, 0), the command of the torque current Iq is determined based on the torque to be output from the motor (hereinafter referred to as "requested torque" or "torque command"). Change the value. If, for example, an inverter provided in front of the motor is controlled based on these command values, an output torque T represented by the following equation (3) can be obtained.

T = E ₀ I _q + (L _d −L _q ) I _d I _q (3) The first term of this equation indicates a torque component generated by the permanent magnet which is a field, that is, a magnet torque. The second term shows the reluctance torque generated by the saliency of the PM motor. Therefore, when the PM motor is a non-salient machine, L _d = L _q and only the first term is _satisfied . When the PM motor is a salient machine, L _d ≠ L _{q and} the second term is generated.

Further, the terminal voltage V of the _{motor, V = ωE 0 + jωL q} I q + jωL d I d ... (4) become. According to this equation, when the rotational speed N of the PM motor and, consequently, the shaft angular velocity ω of the motor increase, the back electromotive force ωE ₀ increases in proportion thereto. Therefore, the back electromotive force ωE
If it allows the increase of _0, the terminal voltage V of the motor is increased by an increase in the counter electromotive voltage? E _0, so that the terminal voltage V of the motor may exceed an allowable power supply voltage (battery voltage) V _B. When the terminal voltage V of the motor exceeds the allowable power supply voltage V _B, the voltage corresponding to the difference is applied to the inverter and the power supply provided between the motor and the power source, these would damage. Hereinafter, the rotational speed which the voltage V reaches the allowable power supply voltage V _B is called the base rotational speed, the rotational speed range above the base rotational speed is referred to as a high speed range. As a method for coping with such a problem, there is a so-called field weakening control. That is, by supplying the field current I _d, by performing control for generating a field magnetomotive force of offsetting field magnetomotive force of the permanent magnet,
The terminal voltage V in the high rpm can be suppressed within the allowable supply voltage V _B. The field current I _d having such a property is called a weak field current. The field weakening current I _d is
As can be seen from the _Id map (FIG. 10) of the field-weakening control, it is determined in advance from the motor rotation speed N and the torque T. When the control is actually performed, this is determined by the torque command and the rotation speed N. by referring to the map, to control the weak field current I _d.

[0007] The field weakening control is disclosed in the 1991 IEEJ Industrial Application Division National Convention "No. 74, Speed control system using flux weakening control of PM motor".

[0008]

The above-mentioned allowable power supply voltage V
_B is a voltage determined solely by the voltage of the battery. Therefore, the state of charge (SOC: State of C
harge) and load condition. Therefore,
When performing the field weakening control of the PM motor, the field weakening current I
There is a problem that _d becomes too large or too small, the efficiency is reduced, or the required torque (torque command) is not accurately realized.

[0009] For example, when the allowable power supply voltage V _B high as viewed from the required torque would flow field weakening current I _d unnecessarily. Shown are as apparent from the vector diagram and the equation (4) in FIG. 9 (b), but lower the terminal voltage V by flowing weak field current I _d, does not contribute to torque generation current (I _d) is As a result, efficiency is reduced.

[0010] Conversely, when the allowable power supply voltage V _B lower as viewed from the requested torque can not flow sufficiently weak field current I _d for suppressing terminal voltage V equal to or less than the allowable power supply voltage V _B In addition, the torque current _Iq for obtaining the required torque cannot be supplied.

The present invention, such has been made as a problem of solving the problem, by using additional information when field weakening control, field weakening in response to changes in the allowable supply voltage V _B it is an object to provide a drive control apparatus of the PM motor can be controlled current I _d. Also, while securing the starting acceleration performance, and to prevent the decrease in efficiency due to a reduction of the allowable supply voltage V _B due to degradation of the SOC.

[0012]

According to the present invention, there is provided a drive control apparatus for a permanent magnet type synchronous motor according to the present invention, comprising means for sequentially detecting a battery voltage, and a maximum voltage value which can be applied to the motor based on the detected battery voltage. Means for calculating, and means for calculating the value of the field weakening current based on at least the calculated maximum voltage value and the required torque required for the motor,
Means for controlling driving of the motor based on the calculated value of the field weakening current.

Further, when controlling the terminal voltage of the motor by PWM control using the inverter device, calculation of the maximum voltage value is executed based on the detected battery voltage and the modulation factor of the PWM control of the inverter device. Features.

[0014] Further, it is characterized by having means for detecting the state of charge (corresponding to SOC) of the battery, and means for limiting the field weakening current when the state of charge detected becomes equal to or less than a predetermined value. I do.

The limitation of the field weakening current is executed / stopped according to a command.

[0016]

In the present invention, the voltage of the battery is sequentially detected, and the maximum voltage value that can be applied to the motor is calculated based on the detected battery voltage. The calculated maximum voltage value is used for calculating the value of the field weakening current together with the required torque (torque command). The drive of the motor is controlled based on the calculated value of the field weakening current. Therefore, even when the battery voltage, that is, the allowable power supply voltage fluctuates due to the SOC of the battery or the motor load, the optimum field-weakening current can be calculated and optimum field-weakening control can be performed in response to the fluctuation. Become. This leads to securing efficiency and suitably realizing the required torque.

Further, by calculating the maximum voltage value based on the detected battery voltage and the modulation factor of the PWM control of the inverter device, the P value using the inverter device is calculated.
When the terminal voltage of the motor is controlled by the WM control (switching control of the inverter constituent elements by the pulse width modulation signal), the above operation can be suitably realized.

Further, when the field weakening current is calculated and set according to the battery voltage as described above, the field weakening current value increases with a decrease in the battery voltage due to, for example, a decrease in the SOC. Then, the efficiency decreases due to an increase in the field weakening current. In the present invention, in order to cope with such a situation, the field weakening current is limited according to the remaining capacity of the battery. In other words, when the remaining capacity of the battery is detected and the field weakening current is limited when the detected remaining capacity is equal to or less than a predetermined value, the remaining capacity decreases (relative SOC decreases). Therefore, even if the battery voltage is reduced, the field-weakening current does not increase, so that the efficiency is prevented from deteriorating. Also in this case, since the torque is secured in the low rotation / high torque range, the starting acceleration performance is secured, and when the motor is used as a drive mechanism of an electric vehicle, the drive feeling is suitably secured. You.

On the other hand, such a limitation on the field weakening current causes an insufficient output torque in a high rotation speed range. Therefore, if the restriction of the field weakening current is executed / stopped according to, for example, a command from the user, the user can perform the operation with an emphasis on efficiency as necessary, or the operation with the emphasis on output. It becomes possible to select whether or not to perform it, and it becomes possible to cope with it more widely at the request of the user.

[0020]

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

FIG. 1 shows a configuration in which the drive control device according to the first embodiment of the present invention is used as a control device for a drive system of an electric vehicle. That is, the drive system of the electric vehicle shown in this figure has a configuration in which the PM motor 10 is driven by the output of the battery 16. The terminal voltage V _B of the battery 16 is converted into three-phase alternating current by an inverter 14 provided between the battery 16 and the motor 10 and supplied to the motor 10. The voltage V output from the inverter 14 is applied to the motor 10.

The drive control device according to the present embodiment includes a battery voltage detecting section 18 connected in parallel to the battery 16,
A first calculation unit 20 connected to the battery voltage detection unit 18;
It has a second operation unit 22 connected to the first operation unit 20 and an inverter controller 24 provided between the second operation unit 22 and the inverter 14.

FIG. 3 shows the second operation unit 2 in this embodiment.
2 is shown.

The second arithmetic unit 22 receives the rotational speed N from the position detector 12 which is attached to the PM motor 10 and detects the rotational phase θ and the rotational speed N of the rotor, and receives a torque command T _ref from a device (not shown). Input (100). Revolution N
There base when the rotation speed N is lower than _B is (102) of the PM motor 10, the second arithmetic unit 22, used as a controlled Equation (3) described above, sets the field current I _d to 0,
Based on a torque command T _ref calculated in accordance with the accelerator and brake operation of the vehicle operator in a circuit (not shown),
The torque current _Iq is calculated (104). Second operation unit 22
Is 0 as the field current command value I _d ^*, the torque current I _q obtained as a torque current command value I _q ^*, respectively output (106). Inverter controller 24
The resulting field current command value I _d ^* (= 0) and with the torque current command value I _q ^*, generates a PWM signal for controlling the inverter 14. At this time, the position detector 12
A process such as coordinate conversion is performed using the rotation phase θ detected by the above.

[0025] When the rotational speed N is based rotational speed N _B or the PM motor 10 (102), the second arithmetic unit 22, in addition to the torque command T _ref, by entering the maximum motor-applied voltage V _MAX (108 ), and calculates the field weakening current command value I _d ^* (110). Therefore, the battery voltage detector 18 detects the terminal voltage V _B of the battery 16, and outputs to the first arithmetic unit 20. The first calculation unit 20 determines the maximum value of the voltage V when the PWM modulation degree in the inverter controller 24 is set to 100%, that is, the inverter 1 by the battery 16.
4 to calculate the maximum motor applied voltage _VMAX . When the inverter controller 24 uses a triangular wave as a carrier and generates a PWM signal by comparing the carrier with a sine wave signal indicating a command for each switching element constituting the inverter 14, The content is V _MAX = (MAX3 / 2√2) V _B.

The calculation (110) of the field weakening current command value I _d ^* in the second calculation unit 22 is performed by the above-described equations (1) to (3).
The torque command T _ref is substituted for the medium torque T, and the maximum motor applied voltage V _MAX is substituted for the terminal voltage V.
_This is performed in the procedure of _{obtaining d} and the torque current _Iq .
Of course, a procedure in which a map is created in advance and this is referred to may be used. Obtained field current I _d
And the torque current I _q, the inverter controller 24 as the field current command value I _d ^* and the torque current command value I _q ^*
(112). Inverter controller 24
Is PWM based on these command values and using the phase θ.
Generate a signal. Note that ω in Expression (1) is obtained from the rotation speed N (ω = 2πN). Further, when the motor 10 is butt <br/> pole machine, it is necessary for calculation of the second term of equation (3), the relationship between L _d -L _q and T, the second arithmetic unit and mapped 22.

The feature of this embodiment, the rotational speed N is the field current control at high rpm as the base rotational speed N _B or more, that weakens the field control is performed using the maximum motor-applied voltage V _MAX It is in. That is, the SOC of the battery 16
When the load of the or motor 10 a battery voltage V _B is varied, in response to this variation supplying optimum field weakening current I _d, it is in that to perform the field control optimum weakening.

As shown in FIG. 2, the field weakening current I _d
As the terminal voltage V decreases,
The efficiency η also decreases. That is, as described above, the primary current of the motor 10 by an increase in weak field current I _d I =
( _Id ² + I _q ² ) ^1/2 increases, and the increase in the current I increases the copper loss and lowers the efficiency η. According to FIG. 2, when the terminal voltage V is equal to or less than the maximum motor applied voltage V _MAX , the efficiency η becomes the best because the field weakening current I _d when V = V _MAX is equal to the command value I _d ^* . This is the case. Therefore, based on the battery voltage V _B , the maximum motor applied voltage V
Calculates the _MAX, lack of field current command I If you define a _d ^*, decrease in efficiency η by passing a field weakening current I _d unnecessarily, weak field current I _d with this Output shortage does not occur.

FIG. 4 shows the configuration of an apparatus according to a second embodiment of the present invention. In this embodiment, an SOC sensor 26 for detecting the SOC of the battery 16 is further provided. The SOC of the battery 16 detected by the SOC sensor 26 is input to the second calculation unit 22. A mode command is further input to the second calculation unit 22 from a switch (not shown) operated by a vehicle operator.

FIG. 5 shows a flow of the operation of the second arithmetic unit 22 in this embodiment. This embodiment is characterized in that steps 114 to 118 are executed after execution of step 110.

That is, when the rotation speed N is equal to or higher than the base rotation speed N _B , after calculating I _d and I _q , it is determined whether the mode command indicates the output mode or the efficiency mode. Is performed (114). If the result of this determination is that the output mode has been set, the process immediately proceeds to step 112;
Move to 6. In step 116, whether SOC detected by the SOC sensor 26 is equal to or less than the predetermined value SOC _0, that is, whether reduction of the SOC is occurring is determined. Proceeds immediately to step 112 if the decrease of the SOC is determined not to have occurred, occurs when it is determined that I _d is limited to a predetermined value I _d0 (118), then proceeds to step 112 .

In this case, it is possible to drive the vehicle in accordance with the preference of the vehicle operator, in which the output is emphasized in some cases and the efficiency is emphasized in other cases. That is, the vehicle operator can limit I _d , and eventually the command value I _d ^*, to the predetermined value I _d0 according to the decrease in the SOC by giving the second operation unit 22 a mode command indicating the efficiency mode. That is, as shown in FIG. 2, when battery voltage V _B decreases in accordance with the decrease in SOC, maximum motor applied voltage V _MAX calculated in step 108 increases, and the value of I _d calculated accordingly Also increase. When output I _d of the increased value as it is as the command value I _d ^*, the efficiency by increasing the current component which does not contribute to torque generation (I _d) decreases. In the present embodiment, it is possible to restrict to the command value I _d ^* to a predetermined value I _d0 response to the decrease of the SOC, the reduction in efficiency due to a decrease in the battery voltage V _B with decreasing SOC can be prevented.

Further, the vehicle operator gives a mode command indicating the output mode to the second arithmetic unit 22 so that the SOC
Irrespective of the decrease of the motor speed, it is possible to obtain a motor output which is not limited by I _{d0 in} a high rotation range. That is, when the above-described field current limitation is performed, as shown in FIG. 7, the output range of the torque T is narrowed to a lower torque side, and as a result, the output is limited. Therefore, in this embodiment, step 116
And an output mode in which the output torque T is omitted.
Can be secured.

Further, the output limitation caused by the field current limitation does not cause a problem as described in, for example, JP-A-5-38003. In this publication, FIG.
As shown in (2), the output torque T of the motor is limited in accordance with the decrease in the SOC. In this figure, TN
In a high rotation range where the maximum output torque in the map is determined by an equal power line (a line in which the output torque T is multiplied by the rotation speed N and the motor output power is constant), the equal power line has a lower power in response to a decrease in the SOC. Switch to line.

In such an output limitation, the output torque T is not limited if the torque command _Tref is low even in a high rotation range, but in this case, a loss occurs because the field weakening control is performed. The rotation range in the base rotational speed N _B vicinity, despite the area where good efficiency, since the output is limited, the vehicle traveling is undesirable.
In the present embodiment, as shown in FIG. 7, the output limitation caused by the field current limitation performed in accordance with the decrease in the SOC functions even in the high-speed and low-torque range, and therefore I _d caused in accordance with the decrease in the SOC. Is suppressed from decreasing due to the increase in the efficiency. In addition, the starting acceleration performance is secured, and the drive feeling is suitably secured. Further, in the rotation range in the base rotational speed N _B near the output limit is not performed, from the surface, good efficiency is obtained.

[0036] In the above respective embodiments, the battery voltage detection unit 18 has detected the terminal voltage V _B of the battery 16, so as to estimate the battery voltage V _B by the vehicle state such as the SOC and the vehicle load You may.

[0037]

As described above, according to the present invention,
Since the field weakening current is controlled according to the change in the allowable power supply voltage, an optimum field weakening current can be obtained irrespective of the fluctuation of the SOC or the fluctuation of the motor load. For example, when the allowable power supply voltage is high, the predetermined efficiency can be maintained without flowing the field current more than necessary, and when the allowable power supply voltage decreases, the current for obtaining the required torque flows. be able to.

Further, since the maximum voltage value is calculated based on the detected battery voltage and the modulation factor of the PWM control of the inverter device, the terminal voltage of the motor is controlled by the PWM control using the inverter device. ,
The above effects can be suitably obtained.

Further, when the field weakening current is calculated and set according to the voltage of the battery, the field weakening current is limited in accordance with the remaining capacity of the battery. Since this does not lead to an increase control of the field weakening current, it is possible to prevent the efficiency from deteriorating. Also in this case, since the torque is secured in the low rotation high torque region, the starting acceleration performance can be secured, and the drive feeling can be suitably secured when the motor is used as a drive mechanism of an electric vehicle.

The limitation of the field weakening current is executed / stopped according to, for example, a command from the user. Therefore, whether the user performs the operation with emphasis on efficiency or the output is emphasized as necessary. It becomes possible to select whether to drive or not, and it becomes possible to cope with it more widely according to the user's request.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a drive control device for a permanent magnet type synchronous motor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a field weakening current, a terminal voltage, and efficiency.

FIG. 3 is a flowchart showing a flow of an operation of a second calculation unit in the embodiment.

FIG. 4 is a block diagram showing a configuration of a drive control device for a permanent magnet type synchronous motor according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing a flow of an operation of a second calculation unit in the embodiment.

FIG. 6 is a diagram showing field current limitation in this embodiment.

FIG. 7 is a diagram showing output limitation in this embodiment.

FIG. 8 is a diagram showing a conventionally known output limitation.

FIG. 9A is a circuit diagram showing an equivalent circuit of a permanent magnet synchronous motor, and FIG. 9B is a vector diagram of the permanent magnet synchronous motor.

FIG. 10 is a diagram illustrating a relationship between a motor speed and a torque when field weakening control is performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Motor 12 Position detector 14 Inverter 16 Battery 18 Battery voltage detection part 20 First operation part 22 Second operation part 24 Inverter controller

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02P 6/08 H02P 5/408

Claims (4)

(57) [Claims] A drive control device for a permanent magnet type synchronous motor that performs field weakening control by applying a field weakening current to a permanent magnet type synchronous motor that receives power supply from a battery when a predetermined condition is satisfied, Means for sequentially detecting the voltage of the battery; means for calculating the maximum voltage value that can be applied to the motor based on the detected voltage of the battery; and weakening at least based on the calculated maximum voltage value and the required torque required for the motor. A drive control device for a permanent magnet synchronous motor, comprising: means for calculating a value of a field current; and means for controlling the drive of the motor based on the calculated value of the field weakening current. 2. When the terminal voltage of a motor is controlled by PWM control using an inverter device, the calculation of the maximum voltage value is performed based on the detected battery voltage and the modulation factor of the PWM control of the inverter device. The drive control device for a permanent magnet synchronous motor according to claim 1, wherein: 3. The apparatus according to claim 1, further comprising: means for detecting a remaining capacity of the battery; and means for limiting a field weakening current when the detected remaining capacity becomes equal to or less than a predetermined value. A drive control device for a permanent magnet type synchronous motor as described in the above. 4. The drive control device for a permanent magnet type synchronous motor according to claim 3, wherein the restriction of the field weakening current is executed / stopped according to a command.