JP4452519B2 - DC brushless motor drive control apparatus and method for vehicle propulsion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize the loss of the whole of a motor in a drive controller of a DC brushless motor for driving the DC brushless motor by using a booster. <P>SOLUTION: As shown in Fig. (c), in a region that the number of target rotations exceeds the number Rb of base rotations, an inverter and the booster are controlled by a field-weakening current and a boosting ratio in which the sum of a field-weakening loss and a boosting loss becomes the minimum. In this manner, the DC brushless motor can be controlled to be driven at the best efficiency as the whole drive control apparatus of the DC brushless motor. That is, in the DC brushless motor using the booster, field-weakening control for minimizing the loss of the motor entirety can be performed. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to a DC brushless motor drive control apparatus and method for vehicle propulsion, and more particularly to a DC brushless motor drive control apparatus for vehicle propulsion suitable for application to an electric vehicle that drives and controls a DC brushless motor via a booster. And a method.

  Conventionally, DC brushless motors (hereinafter also simply referred to as motors) are used in EVs (electric vehicles) and HEVs (hybrid electric vehicles).

  The drive control of the motor is executed by converting the battery voltage Vb of the battery into a motor terminal voltage Vm and a motor current Im by an inverter and supplying the converted voltage to the motor.

  In DC brushless motors, field-weakening control techniques have been proposed to cover a wide range of rotation speed (rotation speed).

  As shown in FIG. 7, the field weakening control technique is a low current in which a motor current Im corresponding to the difference voltage between the motor terminal voltage Vm and the induced voltage (back electromotive voltage) E flows through the field coil to generate a large torque T. This technique is applied when the rotational speed has become higher than the base rotational speed Rb from the rotational range, and the field current (d-axis current) command Id by vector control is increased so that the permanent magnet of the rotor In this control, the output is kept constant by canceling the magnetic flux (main magnetic flux) and suppressing the induced voltage (back electromotive voltage) E.

  However, when field-weakening control is performed, there is a problem that the loss of the motor increases (efficiency deteriorates) due to cancellation of the main magnetic flux.

  A technique for solving this problem is proposed in Patent Document 1. In this technology, a booster is arranged between the battery and the motor, and when the rotational speed is higher than the base rotational speed Rb, the boosted voltage obtained by boosting the battery voltage Vb is supplied to the inverter, thereby controlling the field weakening. The motor is driven with a large torque without performing the above.

Japanese Patent Laid-Open No. 10-66383 (FIG. 1)

  However, in the permanent magnet synchronous drive control device for a motor according to Patent Document 1, since the boost loss in the booster is not taken into consideration, the loss increases especially in the high rotation range when considering the loss of the entire motor. The inventors of this application have found that there is a problem.

  The present invention has been made in consideration of such problems, and a DC brushless motor drive control apparatus and method for vehicle propulsion that can minimize the loss of the entire motor even when a booster is used. The purpose is to provide.

  In this section, for ease of understanding, reference numerals in the attached drawings are used for explanation. Therefore, the contents described in this section should not be construed as being limited to those with the reference numerals.

  The present invention device is a DC brushless motor drive control device for vehicle propulsion driven by a battery 14, wherein the booster 16 boosts the battery voltage Vb of the battery to generate a boosted voltage Vs, and the battery voltage or An inverter 22 that outputs a motor terminal voltage Vm and a motor current Im to the motor 12 with the boosted voltage as an input; in a region where the target rotational speed of the motor exceeds the base rotational speed; A control device 24 for performing field weakening control of the motor, and the control device obtains a field weakening loss corresponding to the field weakening control and a boosting loss corresponding to the boost voltage in accordance with the target rotational speed and target torque. The inverter and the boosting ratio are determined by the field-weakening current and the boost ratio that minimize the sum of the obtained field-weakening loss and boosting loss. And controlling the vessel (the invention according to claim 1).

  The method of the present invention is a DC brushless motor drive control for vehicle propulsion driven by a motor terminal voltage and a motor current output from an inverter with a battery voltage of the battery or a boosted voltage obtained by boosting the battery voltage by a booster as an input. In the method, in a region where the target rotational speed of the motor exceeds the base rotational speed, a field-weakening loss corresponding to field-weakening control and a boosting loss corresponding to the boosting voltage of the booster according to the target rotational speed and target torque And a step of controlling the inverter and the booster by a field weakening current and a boost ratio that minimizes the sum of the determined field weakening loss and boosting loss. Item 2).

  According to the present invention, in a region where the target rotational speed of the DC brushless motor exceeds the base rotational speed, the inverter and the booster are controlled by the field weakening current and the boosting ratio that minimize the sum of the field weakening loss and the boosting loss. As a result, the entire DC brushless motor drive control device can be driven and controlled with the best efficiency. That is, field weakening control that minimizes the loss of the entire motor in a DC brushless motor using a booster can be performed.

  According to the present invention, even when a booster is used when driving a DC brushless motor, the loss of the entire motor can be minimized by using the field weakening control together. The present invention is particularly suitable for application to EV and HEV.

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

  FIG. 1 shows the configuration of a drive control device 10 for a DC brushless motor for vehicle propulsion according to an embodiment of the present invention.

  This drive control device 10 basically includes a DC brushless motor (hereinafter also simply referred to as a motor) 12 having a rotor as a permanent magnet and a stator as a three-phase field, and a battery voltage Vb of 100 [ V] and is driven by a relatively high voltage battery 14 exceeding V].

  The battery voltage Vb of the battery 14 is directly supplied as the input voltage Vin of the inverter 22 when the input voltage of the booster 16 or the semiconductor switch 20 is closed.

  When the switch 20 is in the open state, the boosted voltage Vs (Vs = Br × Vb) obtained by boosting the battery voltage Vb by the booster 16 having the boost ratio Br is supplied as the input voltage Vin of the inverter 22. Note that the input voltage Vin of the inverter 22 is smoothed by the capacitor 23.

  A DC voltage that is an input voltage Vin to the inverter 22 is switched based on a switch signal from the control device 24 in the inverter 22 and converted into a motor terminal voltage Vm that is a three-phase phase voltage and a motor current Im that is a phase current. And supplied to the motor 12. In FIG. 1, the motor terminal voltage Vm and the motor current Im are drawn for only one phase.

  In this case, the control device 24 receives the magnetic pole position of the rotor from the magnetic pole position sensor 26 such as a Hall element, the battery voltage Vb and the inverter input voltage Vin from the voltage sensors 28 and 30, and the phase current Im from the current sensor 32. Are respectively supplied as detection values. The control device 24 can detect the number of rotations of the motor 12 and the like from the temporal change in the magnetic pole position.

  The control device 24 includes a CPU (Central Processing Unit) 40 having arithmetic / control / processing means, a memory 42 {ROM (Read Only Memory) in which programs and maps are stored, and a RAM used as a main memory and the like. (Random Access Memory). }, A timer 44 which is a counting / timer, and an interface (I / F) 46 such as an A / D converter / D / A converter / driver.

  The control device 24 (the CPU 40) controls the driver (driver) in addition to the magnetic pole position, the battery voltage Vb, the inverter input voltage Vin (battery voltage Vb or boosted voltage Vs), the phase current Im, which are the detection values described above. The program is executed in response to various inputs such as the accelerator opening and the shift position related to the above, and the target rotational speed and the target torque, that is, the target output is calculated.

  Then, the control device 24 calculates the inverter input voltage Vin corresponding to the predetermined motor terminal voltage Vm for obtaining the target output, and the d-axis component voltage related to vector control for outputting the predetermined motor terminal voltage Vm. The command Vd and the q-axis component voltage (also referred to as q-axis voltage) command Vq are calculated, and the switching control of the inverter 22 is performed. The d-axis is a field axis (rotor magnetic flux axis), and the q-axis is a torque axis (induced voltage axis) with a phase advanced by 90 ° from this.

  Here, the voltages Vd and Vq, which are command voltages, are calculated by, for example, a well-known vector control voltage equation expressed by the following equations (1) and (2).

Vd = (r + pLd) × Id−ω1 · Lq × Iq (1)
Vq = ω1 · Ld × Id + (r + pLq) × Iq + Ke · ω1 (2)
r: winding resistance, p: differential operator, Ld: d-axis inductance, Id: field current command, ω1: rotating electrical angular velocity command, Lq: q-axis inductance, Iq: torque current command, Ke: phase induced voltage constant

  Prior to switching control of the inverter 22, the control device 24 performs boost control of the booster 16 and open / close control of the switch 20.

  The booster 16 is supplied with a boost voltage Vs required to output a predetermined motor terminal voltage Vm from the control device 24, in other words, a boost ratio Br that generates a predetermined inverter input voltage Vin.

  At this time, the switch 20 is controlled to be opened and closed by the control device 24, and is closed when the motor 12 is rotating at a base rotational speed Rb or less, or when the motor 12 is regenerated due to a driver's brake operation or the like. The battery voltage Vb bypasses the booster 16 and is supplied to the inverter 22, or the regenerative voltage of the motor 12 is supplied to the battery 14 via the inverter 22 that performs a regenerative operation by the control device 24. On the other hand, the switch 20 is opened when the motor 12 is rotating at the base rotational speed Rb or more. When the motor 12 is opened, the boosted voltage Vs obtained by boosting the battery voltage Vb by the booster 16 is supplied to the inverter 22. To be supplied.

  The drive control apparatus 10 for a DC brushless motor for vehicle propulsion according to this embodiment is basically configured and operates as described above. Next, an inverter input voltage Vin for the inverter 22 during vehicle travel is provided. The voltage adjustment operation and the like will be described in detail based on a flowchart executed by the control device 24 shown in FIG.

  In step S1, the motor speed corresponding to the current vehicle speed based on the magnetic pole position sensor 26, the battery voltage Vb from the voltage sensor 28, the inverter input voltage Vin from the voltage sensor 30, and the phase current Im from the current sensor 32 at step S1. And various signals such as the accelerator opening degree related to the operation of the driver.

  Next, in step S2, a target rotational speed corresponding to the target vehicle speed based on the accelerator opening is calculated, and a torque command (also referred to as target torque) T for obtaining the target rotational speed is calculated. Based on the above, a vector control current command (Id, Iq) is calculated.

  Next, in step S3, a voltage command (Vd, Vq) for vector control is calculated based on the above equations (1) and (2).

  Next, in step S4, it is determined whether or not the field current command Id obtained in step S2 is a positive value (Id> 0).

  When the field current command Id is a positive value, it is not necessary to perform field weakening control. Therefore, in step S5, the switch 20 is closed and the battery voltage Vb is supplied as the input voltage Vin of the inverter 22.

  Therefore, in step S6, the inverter 22 to which the battery voltage Vb is supplied as the input voltage Vin is switched and driven based on the voltage command (Vd, Vq) obtained in step S3 to perform feedback control.

  On the other hand, in step S4, if the field current command Id obtained in step S2 is a negative value, it is determined that field weakening control is necessary. In steps S11 to S18, field weakening loss and step-up loss are determined. A redetermination process such as the step-up ratio Br and the field weakening current Id that minimize the sum is performed.

  In this embodiment, as shown in FIG. 3, when the target rotational speed is in the rotational speed region exceeding the base rotational speed Rb, the inverter input voltage Vin is changed from the motor required boosted voltage Vsx described later to the voltage by field weakening control. The boosted voltage Vs is obtained by subtracting the components. When the target rotational speed is equal to or lower than the base rotational speed Rb, the inverter input voltage Vin is set to the battery voltage Vb. In other words, in this embodiment, the motor 12 is driven by the battery voltage Vb when driven and controlled in a region below the base rotational speed Rb, and is boosted voltage when driven and controlled in a region exceeding the base rotational speed Rb. It is configured to be controlled by Vs and field weakening current Id.

  Next, in step S11, the boosted voltage (motor required boosted voltage) Vs (referred to as Vsx) converted from the motor terminal voltage Vm to the inverter input voltage Vin is calculated by the following equation (3), where k is the conversion coefficient. To do.

Vsx = k × Vm = k (Vd ² + Vq ² ) ^1/2 (3)

  If this boosted voltage Vsx is displayed in a voltage vector diagram (the horizontal axis is the q-axis that is the torque axis, and the vertical axis is the d-axis that is the field axis), as shown in FIG. Is expressed by a combined vector of the induced voltage vector ω1Ke on the q axis and the resistance loss vector rIq on the boosted voltage Vsx in the voltage circle display and the inductance loss vector LqIq on the d axis. The

  Next, in step S12, a field weakening loss Pm corresponding to the boosted voltage Vsx is calculated. The field weakening loss Pm can be obtained in advance from the relationship with the boost voltage Vsx using the target output (target torque T × target rotation speed) and the battery voltage Vb as parameters, and is shown in FIG. Thus, the memory 42 stores the field weakening loss Pm with respect to the boost voltage Vsx.

  In step S13, a boost loss Ps corresponding to the boost voltage Vsx obtained in step S11 is calculated. The boost loss Ps can be obtained in advance by the relationship with the boost voltage Vsx using the target output (target torque T × target rotation speed) as a parameter. As shown in FIG. It is stored in the memory 42 as a map of the boost loss Ps.

  In FIGS. 5A and 5B, when the target output is a value outside the map, the desired field weakening loss Pm and boost loss Ps are obtained by interpolation or extrapolation. Can be calculated.

  Next, in step S14, the sum (added value, combined value) Pa (Pa = Pm + Ps) of the field weakening loss Pm calculated in step S12 and the step-up loss Ps calculated in step S13 is calculated and stored in the memory 42. To do.

  Next, in step S15, the boosted voltage Vsx calculated in step S11 is decreased by a predetermined amount, and each time the processing in steps S12 to S14 is repeated to obtain a combined loss (total loss) Pa, and the minimum of the combined loss Pa is determined. Find the value.

  In this case, as shown in FIG. 5C, when the boosted voltage Vsx is decreased, there exists a minimum combined loss Pmin that is the minimum point of the combined loss Pa. The boost voltage Vsx that generates the minimum combined loss Pmin is assumed to be a boost voltage Vs (= inverter input voltage Vin) that is actually generated by the booster 16.

  On the voltage vector diagram of FIG. 4B, the boosted voltage Vs (= Vin) that generates the minimum combined loss Pmin is depicted. This boosted voltage Vs (= Vin) is larger than the battery voltage Vb and is smaller than the required boosted voltage Vsx calculated by the expression (3) when no field weakening control is performed.

  Next, in step S16, the boost ratio Br is set to Br = Vs / Vb in the booster 16 {see the voltage vector diagram of FIG. 4C}.

  In step S17, the battery voltage Vb is boosted to the boosted voltage Vs by the booster 16 and then supplied to the inverter 22 as the inverter input voltage Vin.

  Next, in step S18, as shown in FIG. 4D, the field weakening current Id is calculated on the voltage vector diagram. The field weakening current Id can be calculated by solving the following equations (4) to (6) with reference to the above equations (1) to (3).

Vds = (r + pLd) × Id−ω1 · Lqs × Iqs (4)
Vqs = ω1 · Ld × Id + (r + pLq) × Iqs + Ke · ω1 (5)
Vs = k (Vds ² + Vqs ² ) ^1/2 (6)
Vds: d-axis component voltage at the boosted voltage Vs, Vqs: p-axis component voltage at the boosted voltage Vs, Iqs: torque command current

  Next, in step S6, the calculated field weakening current Id is substituted into the equations (1) and (2), and the d-axis component voltage command Vd and the q-axis component voltage command Vq are recalculated again. The inverter 22 is subjected to switching control based on the voltage command (Vd, Vq).

  The inverter 22 to which the motor input voltage Vin (= Vs) is input is subjected to PWM (pulse width modulation) control by a switching signal based on the d-axis component voltage command Vd and the q-axis component voltage command Vq, and the corresponding motor The terminal voltage Vm and the motor current Im are output to the motor 12. At this time, the control device 24 detects the rotor magnetic pole position from the magnetic pole position sensor 26, the battery voltage Vb and the inverter input voltage Vin from the voltage sensors 28 and 30, and the phase current Im from the current sensor 32, and feeds back the feedback value. The feedback control is performed so that (Vd, Vq) calculated based on the above becomes the voltage command (Vd, Vq).

  Thereafter, the process of step S1 → S6 or step S1 → S4 “No” → S11 → S6 is repeatedly executed in a short time.

  As described above, according to the embodiment described above, the combined loss Pa that is the sum of the field weakening loss Pm and the boosting loss Ps is minimized in the rotation speed region where the target rotation speed exceeds the base rotation speed Rb. Since the inverter 22 and the booster 16 are controlled by the field weakening current Id and the boost ratio Br, it is possible to drive and control the DC brushless motor 12 with the best efficiency as the overall drive controller 10 of the DC brushless motor 12. it can. That is, in the DC brushless motor 12 using the booster 16, field weakening control that minimizes the loss of the entire motor can be performed.

  Specifically, referring to (a) to (c) of FIG. 6, the combined loss (total loss) Pa of this embodiment will be described as compared to the conventional technique. According to the prior art 1 in which field weakening control is performed entirely in the exceeding region, as shown in FIG. 6 (a), the total loss Pa is a considerably large value Pall1 (iron loss + copper loss + weakening) at the allowable maximum rotational speed Rmax. Field loss), as shown in FIG. 6B, in the case of the prior art 2 that controls only the booster without the field weakening control according to Patent Document 1, the total loss Pall2 (Iron loss + Copper loss + Booster loss). On the other hand, in this embodiment to which the present invention is applied, in the rotation speed region exceeding the base rotation speed Rb, as shown in FIG. It can be suppressed to a small total loss Pall3 (iron loss + copper loss + booster loss + field weakening loss) or less.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the contents described in this specification.

It is a block diagram which shows the structure of one Embodiment of this invention. It is a flowchart with which it uses for operation | movement description of the example of FIG. It is a conceptual diagram of the inverter control which concerns on this embodiment. FIG. 2 is a voltage vector diagram used for explaining the operation of the example in FIG. 1. It is explanatory drawing of a field weakening loss, a pressure | voltage rise loss, and a synthetic | combination loss. It is explanatory drawing of contrast of a prior art and the total loss of this embodiment. It is a general explanatory view of field weakening control technology.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... DC brushless motor drive control device 12 ... DC brushless motor 14 ... Battery 16 ... Booster 20 ... Switch 22 ... Inverter 23 ... Capacitor 24 ... Control device 26 ... Magnetic pole position sensor 28, 30 ... Voltage sensor 32 ... Current sensor 40 ... CPU

Claims (2)

In a DC brushless motor drive control device for vehicle propulsion driven by a battery,
A booster that boosts the battery voltage of the battery to generate a boosted voltage;
An inverter that outputs the battery voltage or the boosted voltage as an input and outputs a motor terminal voltage and a motor current to the motor;
In a region where the target rotational speed of the motor exceeds the base rotational speed, a control device that performs control of the boosted voltage of the booster and field weakening control of the motor,
The controller is
A loss sum of a field weakening loss corresponding to the field weakening control and a boosting loss corresponding to the boost voltage in the motor request boost voltage and each boost voltage obtained by reducing the motor request boost voltage by a predetermined amount is calculated as the target Obtained according to the rotational speed and target torque ,
Of the loss sums in the motor required boost voltage and the respective boost voltages obtained by reducing the motor required boost voltage by a predetermined amount, the inverter and the booster are controlled by the field weakening current and the boost ratio that minimize the loss sum. And a DC brushless motor drive control device for vehicle propulsion. A drive control method of a DC brushless motor for vehicle propulsion driven by a battery ,
A booster that boosts the battery voltage of the battery to generate a boosted voltage; and
An output step in which the inverter outputs the motor terminal voltage and the motor current to the motor with the battery voltage or the boosted voltage as inputs; and
The control device includes a control step of performing control of the boosted voltage of the booster and field weakening control of the motor in a region where the target rotational speed of the motor exceeds the base rotational speed,
The control step includes
A loss sum of a field weakening loss corresponding to the field weakening control and a boosting loss corresponding to the boost voltage in the motor request boost voltage and each boost voltage obtained by reducing the motor request boost voltage by a predetermined amount is calculated as the target Obtained according to the rotational speed and target torque,
Of the loss sums in the motor required boost voltage and the respective boost voltages obtained by reducing the motor required boost voltage by a predetermined amount, the inverter and the booster are controlled by the field weakening current and the boost ratio that minimize the loss sum . that controls the door
Drive control method of the DC brushless motor for vehicle propulsion, wherein the this.

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