JPH07107772A - Drive control circuit of permanent magnet-type synchronous motor - Google Patents

Abstract

PURPOSE:To prevent an efficiency drop or an output shortage due to excess or lack of weak field current when a permanent magnet-type synchronous motor is controlled at a weak field. CONSTITUTION:When the number of revolutions N of a motor is the number of revolutions NB of a base or higher, a first calculation part 20 computes a maximum motor-impressed voltage VMAX, which can be output to an inverter 14, on the basis of a battery voltage VB detected by a battery-voltage detection part 18. A second calculation part 22 reads out the impressed voltage VMAX operated by the first calculation part 20, a torque command Tref and the number of revolutions N of the motor, and its computes a weak field current command Id* in the case of a terminal voltage = the applied voltage VMAX. An inverter controller 24 controls the motor at a weak field by the weak-field current command Id*.

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 to perform.

[0002]

2. Description of the Related Art A permanent magnet type synchronous motor (hereinafter referred to as "PM motor" or simply "motor") has a back electromotive force ωE ₀ (E ₀ : magnetomotive force of a permanent magnet used as a field magnet) due to its operation. (Main magnetic flux), ω: motor shaft angular velocity). Therefore, the equivalent circuit per phase of the PM motor can be expressed 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 by using the battery and the inverter, the voltage V is a value obtained by multiplying the battery voltage by the voltage conversion ratio of the inverter.

Further, when the terminal voltage V of this motor is vector-decomposed and expressed using the d-axis voltage V _d and the q-axis voltage V _q , the following equations (1) and (2) are obtained: Further, when the vector diagram is drawn based on the equation (1), assuming that the primary resistance R is sufficiently small, it becomes as shown in FIG. 9 (b). Where L _d is the d-axis inductance and L _q is q
Axial inductance, I _d is d-axis current (field current), I _q
Is the 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, the command value of the field current Id is controlled to a constant value (for example, 0), while the command of the torque current Iq is generated based on the torque to be output from the motor (hereinafter, referred to as “request torque” or “torque command”). Change the value. Based on these command values, for example, by controlling the inverter in front of the motor, it is possible to obtain the output torque T represented by the following equation (3).

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

Further, the terminal voltage V of the motor is V = ωE ₀ + jωL _q I _q + jωL _d I _d (4) From this equation, when the rotational speed N of the PM motor and, consequently, the axial angular velocity ω of the motor increases, the counter electromotive voltage ωE ₀ increases in proportion to this. Therefore, the back electromotive force ωE
_If the increase of ₀ is allowed as it is, the terminal voltage V of the motor rises due to the increase of the counter electromotive voltage ωE ₀ , and the terminal voltage V of the motor exceeds the allowable power supply voltage (battery voltage) V _B. When the terminal voltage V of the motor exceeds the allowable power supply voltage V _B , a voltage corresponding to the difference is applied to the inverter and the power supply provided between the motor and the power supply, and they are damaged. Hereinafter, the rotation speed at which the voltage V reaches the allowable power supply voltage V _B is called the base rotation speed, and the rotation speed region equal to or higher than the base rotation speed is called the high rotation speed region. There is so-called field weakening control as a method of coping with such a defect. That is, by supplying the field current I _d and performing control to generate a field magnetomotive force that reduces the field magnetomotive force of the permanent magnet,
The terminal voltage V in the high rotation range can be suppressed to the allowable power supply voltage V _B or less. 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 I _d map (FIG. 10) of the field weakening control, it is determined in advance from the rotation speed N and the torque T of the motor, and in actual control, the torque command and the rotation speed N The field weakening current I _d is controlled with reference to the map.

The field-weakening control is disclosed in the 1991 National Conference of Industrial Applications of the Institute of Electrical Engineers of Japan, "No. 74, Speed Control System Using Weak-Flux Control of PM Motor".

[0008]

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

For example, when the allowable power supply voltage V _B is high in view of the required torque, the field weakening current I _d is flowed more than necessary. As is clear from the vector diagram shown in FIG. 9B and the equation (4), the terminal voltage V is lowered by flowing the field weakening current I _d , but a current (I _d ) that does not contribute to torque generation is generated. As a result, a decrease in efficiency occurs.

On the contrary, when the allowable power supply voltage V _B is low in view of the required torque, the field weakening current I _d sufficient to keep the terminal voltage V below the allowable power supply voltage V _B cannot be passed. Also, the torque current I _q for obtaining the required torque cannot be passed.

The present invention has been made to solve the above problems, and by using additional information in the field weakening control, the field weakening depending on the change of the allowable power supply voltage V _B. An object of the present invention is to provide a PM motor drive control device capable of controlling the magnetic current I _d . Another object of the present invention is to prevent the efficiency from decreasing due to the decrease in the allowable power supply voltage V _B due to the deterioration of the SOC while ensuring the starting acceleration performance.

[0012]

A drive control device for a permanent magnet type synchronous motor according to the present invention has a means for sequentially detecting a voltage of a battery and a maximum voltage value that can be applied to the motor based on the detected voltage of the battery. A means for calculating, and a 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 driving and controlling the motor based on the calculated value of the field weakening current.

Further, when the terminal voltage of the motor is controlled by PWM control using the inverter device, the maximum voltage value is calculated based on the detected battery voltage and the modulation factor of the PWM control of the inverter device. Characterize.

Further, it is characterized by further comprising means for detecting the remaining capacity of the battery (corresponding to SOC) and means for limiting the field weakening current when the detected remaining capacity becomes less than a predetermined value. To do.

The limiting 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 voltage of the battery. The calculated maximum voltage value is used for calculating the value of the field weakening current together with the required torque (torque command). The motor is drive-controlled based on the calculated value of the field weakening current. Therefore, even when the battery voltage, and therefore the allowable power supply voltage, fluctuates due to the SOC of the battery or the motor load, it is possible to calculate the optimum field weakening current in response to this fluctuation and perform the optimum field weakening control. Become. This leads to ensuring efficiency and suitable realization of required torque.

Further, by executing the calculation of the maximum voltage value based on the detected voltage of the battery and the modulation rate of the PWM control of the inverter device, P 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 element by the pulse width modulation signal), the above-mentioned action can be preferably realized.

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

On the other hand, such limitation of the field weakening current causes a shortage of output torque in a high rotation range. Therefore, if the above-mentioned field weakening current limitation is executed / stopped in accordance with, for example, a command from the user, whether the user should perform efficiency-oriented operation as necessary, or output-oriented operation should be performed. It becomes possible to select whether or not to carry out, and it becomes possible to widely deal with the request of the user.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment 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 power by the 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.

Further, the drive control device according to the present embodiment has 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 the 2nd calculating part 22 connected to the 1st calculating part 20, and the inverter controller 24 provided between the 2nd calculating part 22 and the inverter 14.

FIG. 3 shows the second operation unit 2 in this embodiment.
2 shows the flow of operation.

The second calculation unit 22 is provided with the PM motor 10 and outputs a rotational speed N from a position detector 12 for detecting a rotational phase θ and a rotational speed N of the rotor of the PM motor 10, and a torque command T _ref from a device (not shown). Input (100). Number of revolutions N
Is lower than the base rotation speed N _B of the PM motor 10 (102), the second calculation unit 22 uses the above-mentioned formula (3) as a control formula and sets the field current I _d to 0, and
Based on the torque command T _ref calculated according to the accelerator operation and the brake operation of the vehicle operator in the circuit (not shown),
The torque current I _q is calculated (104). Second calculation unit 22
Outputs 0 as the field current command value I _d ^{* and the} obtained torque current I _q as the torque current command value I _q ^* (106). Inverter controller 24
Generates a PWM signal for controlling the inverter 14 using the obtained field current command value I _d ^* (= 0) and the torque current command value I _q ^* . At that time, the position detector 12
Processing such as coordinate conversion is performed using the rotation phase θ detected by.

When the rotational speed N is equal to or higher than the base rotational speed N _B of the PM motor 10 (102), the second arithmetic unit 22 inputs the maximum motor applied voltage V _MAX in addition to the torque command T _ref (108). ), And the field weakening current command value I _d ^* is calculated (110). Therefore, the battery voltage detector 18 detects the terminal voltage V _B of the battery 16 and outputs it to the first calculator 20. The first calculator 20 uses the maximum value of the voltage V when the PWM modulation degree in the inverter controller 24 is 100%, that is, the battery 16 causes the inverter 1 to operate.
4 calculates the maximum motor applied voltage V _{MAX X} that can be output.
In the inverter controller 24, when a triangular wave is used as a carrier and a PWM signal is generated by comparing this carrier with a sine wave signal indicating a command to each switching element forming the inverter 14, the first
The calculation content in the calculation unit 20 is V _MAX = (√3 / 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 equations (1) to (3).
The torque command T _ref is substituted for the torque T therein, and the maximum motor applied voltage V _MAX is substituted for the terminal voltage V.
The procedure is to obtain _d and the torque current I _q .
Of course, it is also possible to create a map in advance and refer to it. Obtained field current I _d
And the torque current I _q as the field current command value I _d ^* and the torque current command value I _q ^*.
(112). Inverter controller 24
Is PWM according to these command values and using the phase θ.
Generate a signal. Note that ω in the equation (1) is obtained from the rotation speed N (ω = 2πN). Further, when the motor 10 is a non-salient pole machine, the calculation of the second term of the formula (3) is necessary, and therefore the relationship between L _d −L _q and T is mapped and stored in the second calculation unit 22. It is preferable to leave it.

The feature of this embodiment is that field current control in a high rotation range where the rotation speed N is equal to or higher than the base rotation speed N _B , that is, field weakening control is performed using the maximum motor applied voltage V _MAX . It is in. That is, the SOC of the battery 16
When the battery voltage V _B fluctuates due to the load of the motor 10 or the motor 10, the optimum field weakening current I _d is supplied in response to the fluctuation, and the optimum field weakening control is performed.

As shown in FIG. 2, the field weakening current I _d
As the voltage is increased, the terminal voltage V decreases and
The efficiency η also decreases. That is, as described above, the primary current I = of the motor 10 is increased by the increase in the field weakening current I _d.
(I _d ² + I _q ² ) ^1/2 increases, and the increase of this current I increases the copper loss and decreases the efficiency η. Further, according to FIG. 2, the efficiency η is best when the terminal voltage V is equal to or lower than the maximum motor applied voltage V _{MAX because the} field weakening current I _d when V = V _MAX is the command value I _d ^* . That is the case. Therefore, based on the battery voltage V _B , the maximum motor applied voltage V
_{When MAX} is calculated and the field current command I _d ^* is determined by using _MAX , the efficiency η is decreased by flowing the field weakening current I _d more than necessary, and the field weakening current I _d is insufficient. Output shortage due to does not occur.

FIG. 4 shows the configuration of the apparatus according to the second embodiment of the present invention. In this embodiment, an SOC sensor 26 that detects 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 the vehicle operator.

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

That is, when the rotation speed N is equal to or higher than the base rotation speed N _B, it is determined whether the mode command commands the output mode or the efficiency mode after the calculation of I _d and I _q. (114). As a result of this determination, if the output mode is set, the process immediately proceeds to step 112, and if the efficiency mode is set, step 11 is set.
Go to 6. In step 116, it is determined whether the SOC detected by the SOC sensor 26 is less than or equal to a predetermined value SOC _0, that is, whether or not the SOC has decreased. If it is determined that the SOC has not decreased, the process immediately proceeds to step 112. If it is determined that the SOC has decreased, I _d is limited to the predetermined value I _d0 (118), and then the process proceeds to step 112. .

In this case, it is possible to drive with emphasis on output in some cases and efficiency in other cases according to the preference of the vehicle operator. That is, the vehicle operator can limit the I _d , and thus 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 the battery voltage V _B decreases as the SOC decreases, the maximum motor applied voltage V _MAX calculated in step 108 increases, and the value of I _d calculated accordingly. Also increases. If the increased value of I _d is output as the command value I _d ^* as it is, the efficiency decreases due to the increase of the current component (I _d ) that does not contribute to the torque generation. In the present embodiment, the command value I _d ^* can be limited to the predetermined value I _{d0 according} to the decrease in SOC, so that it is possible to prevent the efficiency decrease due to the decrease in battery voltage V _B due to the decrease in SOC.

Further, the vehicle operator gives a mode command indicating the output mode to the second computing section 22, so that the SOC is
Irrespective of the decrease in the output, a motor output without limitation by I _d0 can be obtained in the high rotation range. That is, when the above-described field current limitation is performed, the output range of the torque T is narrowed to the low torque side as shown in FIG. 7, resulting in output limitation. Therefore, in this embodiment, step 116
And an output mode in which 118 is omitted are provided, and the output torque T
Is available.

Further, the output limitation caused by the field current limitation does not cause the trouble described in, for example, Japanese Patent Laid-Open No. 5-38003. In this publication, etc., FIG.
As shown in, the output torque T of the motor is limited according to the decrease in SOC. In this figure, T-N
In the high rotation range where the maximum output torque in the map is determined by the equal power line (the line where the motor output power that is the product of the output torque T and the rotational speed N is constant), the equal power line becomes lower in power as the SOC decreases. Switch to the line.

With such output limitation, if the torque command T _ref is low even in the high rotation range, the output torque T is not limited, but in that case as well, the field-weakening control is performed, which causes a loss. Further, the middle rotation speed region near the base rotation speed N _B is not preferable in terms of vehicle running because the output is limited although it is a region where good efficiency is obtained.
In the present embodiment, the output restriction caused by field current limiting is performed with the SOC decreases, as shown in FIG. 7, to function at high rotation and low torque region, occurring with a decrease of SOC I _d The decrease in efficiency due to the increase of In addition, the starting acceleration performance is secured, and the drive feeling is suitably secured. In addition, since the output is not limited in the middle rotation range near the base rotation speed N _B , good efficiency can be obtained from this aspect as well.

In each of the above embodiments, the battery voltage detector 18 detects the terminal voltage V _B of the battery 16, but the battery voltage V _B is estimated according to the vehicle state such as SOC and vehicle load. May be.

[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, the optimum field weakening current can be obtained regardless of the fluctuation of the SOC and the fluctuation of the motor load. For example, when the permissible power supply voltage is high, the specified efficiency can be maintained without passing the weakening field current more than necessary, and conversely, when the permissible power supply voltage drops, the current for obtaining the required torque is passed. be able to.

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

Further, when the field weakening current is calculated and set in accordance with the voltage of the battery, the field weakening current is limited in accordance with the remaining capacity of the battery, so that the battery voltage decreases due to the decrease in the remaining capacity. Since it does not lead to the increase control of the field weakening current, efficiency deterioration can be prevented. Also in this case, since the torque is secured in the low rotation and high torque range, the starting acceleration performance can be secured, and the drive feeling can be suitably secured when the motor is used as the drive mechanism of the electric vehicle.

Since the field weakening current is limited / executed in accordance with, for example, a command from the user, whether the user performs the operation focusing on efficiency or the output focusing is emphasized. It becomes possible to select whether or not to drive, and it is possible to widely deal with the request of the user.

[Brief description of 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 operations of a second arithmetic unit in this 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 operations of a second arithmetic unit in this 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 type synchronous motor, and FIG. 9B is a vector diagram of the permanent magnet type synchronous motor.

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

[Explanation of symbols]

 10 Motor 12 Position Detector 14 Inverter 16 Battery 18 Battery Voltage Detection Unit 20 First Calculation Unit 22 Second Calculation Unit 24 Inverter Controller

Claims (4)

[Claims] 1. A drive control device for a permanent magnet type synchronous motor for performing field weakening control by applying a field weakening current to a permanent magnet type synchronous motor supplied with power from a battery when a predetermined condition is satisfied, Means for sequentially detecting the battery voltage, means for calculating the maximum voltage value that can be applied to the motor based on the detected battery voltage, and weakening based on at least the calculated maximum voltage value and the required torque required for the motor. A drive control device for a permanent magnet type synchronous motor, comprising: a means for calculating a value of a field current; and a means for driving and controlling a motor based on the calculated value of the field weakening current. 2. When controlling the terminal voltage of the motor by PWM control using an inverter device, the 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. The drive control device for a permanent magnet type synchronous motor according to claim 1. 3. The battery according to claim 1, further comprising means for detecting the remaining capacity of the battery, and means for limiting the field weakening current when the detected remaining capacity is equal to or less than a predetermined value. A drive control device for the permanent magnet type synchronous motor described. 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.