JP2017070048A - Motor drive control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize both of stabilizing the output voltage of a converter and improving the efficiency of a motor drive control system, in the system including the converter.SOLUTION: A converter 15 converts a voltage of a battery B into a DC voltage VH with a step-up ratio of 1.0 or higher, thus outputting to a power line 7. A voltage instruction value of the converter 15 is set by avoiding a given voltage range for which the step-up ratio of the converter 15 is nearby 1.0. In a case where an optimal voltage falls outside of the voltage range, the optimal voltage being a DC voltage VH with which an estimation value of a total loss in a system in a present operation state of motor-generators MG 1, MG 2, the voltage instruction value of the converter 15 is set in accordance with the optimal voltage. In a case where the optimal voltage is within the voltage range, the voltage instruction value of the converter 15 is set, of a DC voltage for which the step-up ratio is 1.0 and a given voltage on a higher voltage side than the voltage range, so that an estimation value of the total loss is less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric motor drive control system, and more particularly to an electric motor drive control system configured to include a converter capable of variably controlling a DC voltage.

  Japanese Patent Laid-Open No. 2007-325351 (Patent Document) discloses a configuration in which a DC voltage variably controlled by a converter is converted into an AC voltage for driving and controlling an AC motor by an inverter as one type of motor drive control system for driving the AC motor. 1) and the like.

  In the electric motor drive control system of Patent Document 1, there is described control for setting the output voltage command value of the converter so that the total sum of power loss in the battery, converter, inverter and motor generator is minimized.

JP 2007-325351 A

  In the converter configured by the boost chopper circuit shown in Patent Document 1, the voltage conversion ratio (boost ratio) is controlled by the on / off control of the switching elements of the upper arm and the lower arm. However, in the step-up chopper circuit, there is a concern that the output voltage fluctuates due to a decrease in controllability of the output voltage in a region where the step-up ratio is close to 1.0.

  In the motor drive control system, it is important to prevent fluctuations in the output voltage of the converter because it leads to fluctuations in the output of the motor. Therefore, in a predetermined voltage region where the boost ratio is close to 1.0, upper arm on control in which the upper arm switching element is turned on in priority to the stability of the output voltage may be applied.

  For this reason, when the upper arm on control is simply applied when the voltage command value of the converter set by the control described in Patent Document 1 is within the voltage range, the stability of the output voltage is secured. Therefore, there is a concern that the efficiency of the system will decrease.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to improve the stability of the output voltage of the converter and the efficiency of the system in the motor drive control system including the converter. Is to control the converter so as to achieve both.

  In one aspect of the present invention, an electric motor drive control system includes a power storage device, a converter, an inverter, and a voltage setting unit for setting a voltage command value of the converter. The converter converts the voltage of the power storage device into a DC voltage having a step-up ratio of 1.0 or more according to the voltage command value, and outputs it to the DC power supply wiring. The inverter performs power conversion between the DC voltage of the DC power supply wiring and the AC voltage that drives the motor by a plurality of switching elements so that the motor operates according to the operation command. The voltage setting means includes voltage range limiting means, loss estimation means, and first to third setting means. The voltage range limiting means prohibits setting the voltage command value within a predetermined voltage range in which the boost ratio is larger than 1.0 and smaller than the predetermined value. The loss estimation means is a DC voltage that minimizes an estimated value of total power loss including power loss in the power storage device, converter, inverter, and motor in the current operating state of the motor based on preset loss characteristics. Find the optimal voltage. The first setting means sets the voltage command value to the optimum voltage when the optimum voltage is outside the predetermined voltage range. In the second setting means, when the optimum voltage is within the predetermined voltage range, the estimated value of the total power loss when the step-up ratio is 1.0 is determined so that the DC voltage is a predetermined voltage higher than the predetermined voltage range. When the voltage is higher than the estimated value of the total power loss when the voltage is used, the voltage command value is set to a predetermined voltage. In the third setting means, when the optimum voltage is within the predetermined voltage range, the estimated value of the total power loss when the step-up ratio is 1.0 is the total power loss when the DC voltage is the predetermined voltage. When it is lower than the estimated value, the voltage command value is set so that the boost ratio is 1.0.

  According to the above motor drive control system, it is possible to avoid setting the voltage command value in the voltage range where the step-up ratio is low by the voltage range limiting means, so that the controllability of the DC voltage (system voltage VH) is reduced in the voltage range. Therefore, it is possible to prevent the torque fluctuation of the electric motor from occurring. Further, when the DC voltage (system voltage VH) cannot be controlled to the optimum voltage at which the estimated value of the total loss is minimized by the voltage range limiting means, when the boost ratio becomes 1.0 (upper arm on control), While the total loss when the voltage is controlled to a predetermined voltage by the converter is reduced, the DC voltage can be controlled. Thereby, it is possible to achieve both the stability of the DC voltage (system voltage VH) output from the converter and the improvement of the efficiency of the motor drive control system.

  According to this invention, in an electric motor drive control system including a converter, the converter can be controlled so as to achieve both stability of the output voltage of the converter and improvement of the efficiency of the system.

It is a block diagram explaining the structure of the hybrid vehicle shown as an example of application of the electric motor drive control system by embodiment of this invention. FIG. 2 is a functional block diagram for explaining setting of operation command values of an engine and a motor generator shown in FIG. 1. It is a functional block diagram for demonstrating the setting of the voltage command value of a converter. It is a functional block diagram for demonstrating control of the inverter and converter which were shown by FIG. FIG. 4 is a functional block diagram for further explaining the configuration of a loss estimation unit shown in FIG. 3. It is a conceptual diagram for demonstrating the voltage area | region where upper arm ON control is applied to the converter shown by FIG. 2 is a flowchart illustrating a control process for setting a voltage command value for the converter shown in FIG. 1. It is a conceptual diagram which shows the characteristic of a total loss in the case where a voltage command value is set by S130 of FIG. It is a conceptual diagram which shows the characteristic of the total loss in the case where a voltage command value is set by S170 of FIG. It is a conceptual diagram which shows the characteristic of the total loss in the case where a voltage command value is set by S180 of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

(System configuration)
FIG. 1 is a block diagram illustrating a configuration of a hybrid vehicle 100 shown as an application example of an electric motor drive control system according to an embodiment of the present invention.

  Referring to FIG. 1, hybrid vehicle 100 includes a control device 50, an engine 110, a power split mechanism 120, motor generators MG <b> 1 and MG <b> 2, a speed reducer 130, a drive shaft 140 and wheels (drive wheels) 150. Is provided.

  The engine 110 is constituted by, for example, an internal combustion engine such as a gasoline engine or a diesel engine. The engine 110 is provided with a rotation speed sensor 112 that detects the engine rotation speed. The output of the rotation speed sensor 112 is sent to the control device 50.

  Power split device 120 is configured to be able to split the power generated by engine 110 into a route to drive shaft 140 and a route to motor generator MG1. As the power split mechanism 120, a planetary gear mechanism having three rotation shafts of a sun gear, a planetary gear, and a ring gear can be used. For example, in the planetary gear mechanism, the rotor of motor generator MG1 is connected to the sun gear, the output shaft of engine 110 is connected to the planetary gear, and output shaft 125 is connected to the ring gear. The output shaft 125 connected to the rotation shaft of the motor generator MG2 is connected to a drive shaft 140 for rotationally driving the drive wheels 150 via the speed reducer 130. A reduction gear for the rotation shaft of motor generator MG2 may be further incorporated.

  Motor generator MG <b> 1 operates as a generator driven by engine 110 and operates as an electric motor that starts engine 110, and is configured to have both functions of an electric motor and a generator.

  Similarly, motor generator MG2 is incorporated into hybrid vehicle 100 for generating vehicle driving force whose output is transmitted to drive shaft 140 via output shaft 125 and reduction gear 130. Further, motor generator MG2 is configured to have a function for the electric motor and the generator so as to perform regenerative power generation by generating an output torque in a direction opposite to the rotation direction of drive wheel 150.

  Next, a configuration for driving and controlling motor generators MG1 and MG2 will be described.

  Hybrid vehicle 100 further includes a traveling battery B, smoothing capacitors C0 and C1, a converter 15, and inverters 20 and 30.

  The traveling battery B corresponds to the “power storage device” and is configured by a secondary battery such as nickel metal hydride or lithium ion. Alternatively, an electric double layer capacitor or the like can be applied as the “power storage device” instead of the battery B for traveling.

  The battery voltage VB output from the traveling battery B is detected by the voltage sensor 10, and the battery current IB input / output to / from the traveling battery B is detected by the current sensor 11. Furthermore, the temperature sensor 12 is provided in the battery B for driving | running | working. Battery voltage VB, battery current IB and battery temperature TB detected by voltage sensor 10, current sensor 11 and temperature sensor 12 are output to control device 50.

  The smoothing capacitor C1 is connected between the low-voltage power line 5 and the high-voltage power line 6. A relay (not shown) between the positive terminal of the traveling battery B and the power line 6 and between the negative terminal of the traveling battery B and the power line 5 is turned on when the vehicle is driven and turned off when the vehicle is stopped. ) Is provided.

  Converter 15 includes a reactor L1 and power semiconductor elements (hereinafter, referred to as “switching elements”) Q1 and Q2 that are subjected to switching control. Reactor L1 is connected between a connection node of switching elements Q1 and Q2 and power line 6. The smoothing capacitor C0 is connected between the high voltage side power line 7 and the power line 5 (low voltage side).

  Switching elements Q 1 and Q 2 are connected in series between power line 7 and power line 5. Switching elements Q1 and Q2 are turned on and off by control signals S1 and S2 from control device 50. As the switching element, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, a power bipolar transistor, or the like can be used. Anti-parallel diodes D1, D2 are arranged for switching elements Q1, Q2.

  The DC voltage sides of inverters 20 and 30 are connected to converter 15 via common power line 5 and power line 7. The DC voltage VH between the power lines 5 and 7 is hereinafter also referred to as “system voltage VH”. System voltage VH corresponds to the output voltage of converter 15. That is, the power line 7 corresponds to “DC power supply wiring”.

  Inverter 20 includes U-phase arm 22, V-phase arm 24, and W-phase arm 26 provided in parallel between power line 7 and power line 5. Each phase arm is composed of switching elements connected in series between power line 7 and power line 5. For example, U-phase arm 22 includes switching elements Q11 and Q12, V-phase arm 24 includes switching elements Q13 and Q14, and W-phase arm 26 includes switching elements Q15 and Q16. Further, antiparallel diodes D11 to D16 are connected to switching elements Q11 to Q16, respectively. On / off of switching elements Q11-Q16 is controlled by control signals S11-S16 from control device 50.

  Motor generator MG1 includes a U-phase coil winding U1, a V-phase coil winding V1 and a W-phase coil winding W1 provided on the stator, and a rotor (not shown). One ends of the U-phase coil winding U1, the V-phase coil winding V1, and the W-phase coil winding W1 are connected to each other at a neutral point N1, and the other ends are connected to the U-phase arm 22, the V-phase arm 24, and the inverter 20 Each is connected to W-phase arm 26. Inverter 20 performs bidirectional power conversion between the output side of converter 15 and motor generator MG1 by on / off control (switching control) of switching elements Q11-Q16 in response to control signals S11-S16 from control device 50. Do.

  Specifically, inverter 20 can convert a DC voltage received from power line 7 into a three-phase AC voltage according to switching control by control device 50, and output the converted three-phase AC voltage to motor generator MG1. Thereby, motor generator MG1 is driven to generate a designated torque. Further, inverter 20 receives the output of engine 110 and converts the three-phase AC voltage generated by motor generator MG1 into a DC voltage in accordance with switching control by control device 50, and outputs the converted DC voltage to power line 7. it can.

  Inverter 30 is configured similarly to inverter 20, and includes switching elements Q21 to Q26 that are on / off controlled by control signals S21 to S26, and antiparallel diodes D21 to D26.

  Motor generator MG2 is configured similarly to motor generator MG1, and includes a U-phase coil winding U2, a V-phase coil winding V2 and a W-phase coil winding W2 provided on the stator, and a rotor (not shown). . As with motor generator MG1, one end of U-phase coil winding U2, V-phase coil winding V2, and W-phase coil winding W2 are connected to each other at neutral point N2, and the other end is a U-phase arm of inverter 30. 32, V-phase arm 34 and W-phase arm 36, respectively.

  Inverter 30 performs bidirectional power conversion between the output side of converter 15 and motor generator MG2 by on / off control (switching control) of switching elements Q21-Q26 in response to control signals S21-S26 from control device 50. .

  Specifically, inverter 30 can convert the DC voltage on power line 7 into a three-phase AC voltage according to switching control by control device 50, and output the converted three-phase AC voltage to motor generator MG2. Thereby, motor generator MG2 is driven to generate a designated torque. In addition, inverter 30 converts the three-phase AC voltage generated by motor generator MG2 by receiving the rotational force from drive wheel 150 during regenerative braking of the vehicle into a DC voltage according to switching control by control device 50, and the converted DC voltage The voltage can be output to the converter 15.

  Each of motor generators MG1, MG2 is provided with a current sensor 27 and a rotation angle sensor (resolver) 28. Rotation angle sensor 28 detects a rotation angle θ of a rotor (not shown) of motor generators MG 1, MG 2 and sends the detected rotation angle θ to control device 50. Control device 50 can calculate rotation speeds Nm1 and Nm2 of motor generators MG1 and MG2 based on rotation angle θ. In the embodiment of the present invention, the term “number of revolutions” refers to the number of revolutions per unit time (typically per minute) unless otherwise specified.

  The voltage sensor 13 detects the voltage across the smoothing capacitor C 0, that is, the system voltage VH, and outputs the detected value to the control device 50.

  The system voltage VH, the motor current MCRT (1) of the motor generator MG1 and the rotor rotation angle θ (1), and the motor current MCRT (2) and the rotor rotation angle θ (2) of the motor generator MG2 detected by these sensors. ) Is input to the control device 50.

  Further, the control device 50 includes an accelerator operation amount Acc that is a detected value of an operation amount of an accelerator pedal (not shown) by a driver, a brake operation amount Brk that is a detected value of an operation amount of a brake pedal (not shown), In addition, a vehicle speed SP that is a detection value of a vehicle speed sensor (not shown) is input.

  In addition, the control device 50 receives information such as a charge rate (SOC: State of Charge) and input powers Win and Wout indicating charging / discharging restrictions regarding the battery B for traveling. Thus, control device 50 has a function of limiting power consumption and generated power (regenerative power) in motor generators MG1 and MG2 as necessary so that overcharge or overdischarge of battery B for traveling does not occur. .

  A control device 50 including an electronic control unit (ECU) includes a microcomputer (not shown), a RAM (Random Access Memory) 51, and a ROM (Read Only Memory) 52. The control device 50 controls each device so that the hybrid vehicle 100 travels according to the driver operation. Details of the function of the control device 50 will be described later.

  In the present embodiment, the mechanism for switching the switching frequency in the inverter control by the single control device (ECU) 50 has been described. However, the same control configuration is realized by the cooperative operation of the plurality of control devices (ECU). Is also possible.

  Next, operations of converter 15 and inverters 20 and 30 in drive control of motor generators MG1 and MG2 will be described.

  In converter 15, on / off of switching elements Q 1, Q 2 is controlled according to control signals S 1, S 2 from control device 50. Similarly, on / off of switching elements Q11-Q16 in inverter 20 and on / off of switching elements Q21-Q26 in inverter 30 are controlled by control signals S11-S16 and S21-S26 from control device 50, respectively.

  The voltage VB smoothed by the smoothing capacitor C0 is input to the input side of the converter 15. The converter 15 is configured to perform bidirectional DC voltage conversion between the input-side voltage VB and the output-side system voltage VH by on / off control of the switching elements Q1 and Q2.

  The step-up ratio (VH / VB) by converter 15 is controlled to 1.0 or more in accordance with the duty ratio of switching elements Q1, Q2. Basically, the step-up ratio> 1.0 is controlled by controlling the switching element Q2 to be turned on and off within each switching period. In other words, converter 15 has a boosting function and can drive motor generators MG1 and MG2 by DC voltage VH higher than voltage VB. The step-up ratio increases as the ON period ratio of the lower arm element (switching element Q2) increases.

  Particularly, the battery B is charged (MG1 and MG2 is regenerated) and discharged (MG1 and MG2) by turning on and off the upper arm element (switching element Q1) in each switching cycle in a complementary manner with the lower arm element (switching element Q2). The system voltage VH can be controlled in accordance with any of the power running).

  By executing “upper arm on control” with the upper arm element (switching element Q1) fixed on and the lower arm element (switching element Q2) fixed off, VH = VB (boost ratio = 1. 0), the step-up function can be turned off in a state where a bidirectional energization path is secured.

  Smoothing capacitor C0 smoothes the DC voltage (system voltage) from converter 15 and supplies the smoothed DC voltage to inverters 20 and 30. The setting of the torque command values Tqcom (1) and Tqcom (2) will be described in detail later.

  Outputs of motor generators MG1 and MG2 are controlled according to torque command values Tqcom (1) and Tqcom (2). The inverter 30 outputs a torque according to the torque command value Tqcom (2) by the on / off operation (switching operation) of the switching elements Q21 to Q26 in response to the control signals S21 to S26 from the control device 50. Generator MG2 is driven.

  Similarly to the operation of inverter 30 described above, inverter 20 has motor generator MG1 controlled by torque command value Tqcom (1) by on / off control of switching elements Q11-Q16 according to control signals S11-S16 from control device 50. Power conversion is performed so that torque according to the output is output.

  Next, traveling control of the hybrid vehicle 100 by the control device 50 will be described with reference to FIGS. 2 is implemented by software processing by execution of a predetermined program of the control device 50 and / or hardware processing by a built-in dedicated electronic circuit. Shall be.

  FIG. 2 is a functional block diagram for explaining setting of operation commands of engine 110 and motor generators MG1, MG2.

  Referring to FIG. 2, operation command generation unit 300 generates command values for engine 110 and motor generators MG <b> 1 and MG <b> 2 so that traveling according to a driver operation is executed.

  Specifically, the operation command generation unit 300 calculates drive torque necessary for vehicle travel based on the accelerator operation amount Acc, the brake operation amount Brk, and the vehicle speed SP. When the braking torque is required by the brake operation by the driver, the driving torque is set to a negative value.

  Operation command generation unit 300 determines an optimal output distribution between engine 110 and motor generators MG1 and MG2 for applying the drive torque to drive shaft 140, and motor generators MG1 and MG2 according to the determined output distribution. And the operation command of the engine 110 are generated.

  The operation command for engine 110 includes, for example, target engine speed Ne * and target engine torque Te *. Engine control unit 350 controls an actuator group (fuel injection valve, spark plug, intake valve, exhaust valve, etc.) of engine 110 according to target engine speed Ne * and target engine torque Te * from operation command generation unit 300. . Thereby, the rotation speed and torque of engine 110 are controlled in accordance with target engine rotation speed Ne * and target engine torque Te *.

  The operation commands for motor generators MG1 and MG2 include torque command Tqcom (1) for motor generator MG1 and torque command value Tqcom (2) for motor generator MG2.

  FIG. 3 is a functional block diagram for explaining setting of voltage command value VH * of converter 15.

  Referring to FIG. 3, VH command generation unit 400 sets voltage command value VH * based on rotation speeds Nm1, Nm2 of motor generators MG1, MG2 and torque command values Tqcom (1), Tqcom (2). . In setting the voltage command value VH *, the voltage command value VH * is set so as to suppress the loss of the entire system by referring to the loss estimator 500 similar to that of Patent Document 1. Details of the setting of the voltage command value VH * will be described later.

  FIG. 4 is a functional block diagram for explaining the control of converter 15 and inverters 20 and 30.

  Referring to FIG. 4, converter control unit 410 generates control signals S1, S2 for converter 15 such that system voltage VH is controlled in accordance with voltage command value VH *. For example, converter control unit 410 performs feedforward control according to a theoretical boost ratio that is a ratio of voltage command value VH * and voltage VB (input voltage), and deviation ΔVH (ΔVH = VH *) of system voltage VH with respect to voltage command value VH *. The duty ratios of the switching elements Q1 and Q2 are calculated in combination with feedback control based on (−VH). Further, control signals S1, S2 are generated so that switching elements Q1, Q2 are alternately turned on and off according to the calculated duty ratio.

  The MG control unit 420 includes motor currents MCRT (1) and MCRT (2) detected by the current sensor 27, rotor rotation angles θ (1) and θ (2) detected by the rotation angle sensor 28, and a system voltage VH. Based on the above, the output torque of motor generators MG1, MG2 is controlled. Specifically, switching elements Q11 to Q16, Q21 to Q26 of inverters 20 and 30 are controlled so that the output torque of motor generators MG1 and MG2 is controlled according to torque command values Tqcom (1) and Tqcom (2). Control signals S11 to S16, S21, and S26 for on / off control are generated.

  For example, the output torque of motor generators MG1, MG2 is controlled by feedback control of d-axis current and q-axis current calculated from motor currents MCRT (1), MCRT (2) and rotor rotation angles θ (1), θ (2). Is controlled. As described in Patent Document 1, current feedback control can be realized by switching elements Q11 to Q16 and Q21 to Q26 according to pulse width modulation control (PWM control). Alternatively, the control signals S11 to S16, S21, and S26 can be generated so that the output torque of the motor generators MG1 and MG2 is controlled by the rectangular wave voltage control described in Patent Document 1.

  Thus, by controlling the outputs of motor generators MG1 and MG2 according to torque command values Tqcom (1) and Tqcom (2), hybrid vehicle 100 generates vehicle driving force due to power consumption in motor generator MG2. The driver operates the generation of the charging power of the traveling battery B by the power generation by the motor generator MG1 or the power consumption of the motor generator MG2, and the generation of the charging power of the traveling battery B by the regenerative braking operation (power generation) by the motor generator MG2. And it can execute suitably according to the driving state of vehicles.

(Voltage command value setting)
The setting of the voltage command value VH * by the VH command generation unit 400 shown in FIG. 3 will be described in more detail.

FIG. 5 is a block diagram illustrating the configuration of loss estimation section 500 shown in FIG.
Referring to FIG. 5, loss estimation unit 500 includes a battery loss estimation unit 550, a converter loss estimation unit 560, an inverter loss estimation unit 570, and an MG loss estimation unit 580.

The battery loss estimation unit 550 has a loss map 555 created in advance. Loss map 555 can estimate input battery operating conditions (rotation speed, torque) of motor generators MG1 and MG2, system voltage VH and battery loss Plb. The battery loss Plb is mainly Joule loss due to internal resistance, and is indicated by IB · r ² using the internal resistance value r and the battery current IB.

  The battery current IB is obtained by superimposing a ripple current (AC component) ΔIBr on an average current (DC component) IBave. This ripple current ΔIBr increases according to the voltage difference | VH−VB | between system voltage VH and battery voltage VB. The input / output power from the battery indicated by the product of the average current IBave and the battery voltage VB corresponds to the total power consumption or total power generated by each motor generator MG.

  Therefore, similarly to Patent Document 1, paying attention to the battery average current (DC component) and ripple current (AC component), based on the torque × rotational speed of motor generators MG1 and MG2 and the voltage difference | VH−VB | Thus, the battery loss Plb can be calculated.

  Converter loss estimator 560 has a loss map 565 created in advance. Loss map 565 estimates the operating state (torque, rotation speed) of motor generators MG1, MG2, and converter loss Plcv at system voltage VH and battery voltage VB. The loss in converter 15 is mainly the sum of the loss in switching elements Q1 and Q2 and the loss in reactor L1. In either case, the loss decreases as the converter passing current (that is, the battery current IB) decreases and the system voltage VH decreases. Further, when the ripple current ΔIBr increases, the loss depending on the square of the current increases, so the voltage difference | VH−Vb | is one of the factors that determine the converter loss Plcv.

  Therefore, similarly to Patent Document 1, the converter loss Plcv can also be estimated based on the battery average current IBave, that is, the operating state (torque × rotational speed) of MG1 and MG2, and the voltage difference | VH−VB |.

  The inverter loss estimator 570 and the MG loss estimator 580 can be integrally configured by a loss map 575 created in advance. Loss map 575 estimates the sum of inverter loss and MG loss Plmg1 + Priv1 (or Plmg2 + Plib2) from the input operating states (rotation speed, torque) of motor generators MG1 and MG2 and system voltage VH.

  The inverter losses in the inverters 20 and 30 are mainly on-loss and switching loss in the switching element, and become smaller as the current flowing through the switching element is smaller and the system voltage VH is lower. Further, in consideration of the switching of the control method described in Patent Document 1, the inverter loss Priv1 in the inverter 20 or the inverter 30 is determined from the operating state (torque, rotation speed) and system voltage of the motor generators MG1 and MG2. Can be estimated.

  On the other hand, the MG loss in motor generators MG1 and MG2 is the sum of the copper loss caused by the current flowing through each phase coil winding and the iron loss caused by the change in the magnetic flux of the iron core. For this reason, the smaller the current flowing through each phase coil winding, the smaller the MG loss. Therefore, MG losses Pmg1 and Pmg2 in motor generators MG1 and MG2 can be estimated based on the operating states (rotation speed and torque) of motor generators MG1 and MG2.

  Therefore, as in Patent Document 1, the sum of inverter loss and MG loss Plmg1 + Plib1 and Plmg2 + Priv2 is estimated for the operating state (rotation speed, torque) of motor generators MG1 and MG2 and the input of system voltage VH. The loss map 575 that has been converted into a data can be created in advance.

  Adder 590 includes battery loss Plb from battery loss estimator 550, converter loss Plcv from converter loss estimator 560, sum of inverter loss and MG loss from inverter loss estimator 570 and MG loss estimator 580, Plmg1 + Priv1 And Plmg2 + Plib2 are added to calculate the total power loss Pls (hereinafter also referred to as total loss Pls) in the entire motor drive control system.

  FIG. 6 is a conceptual diagram for explaining a voltage region where upper arm-on control is applied to converter 15.

  Referring to FIG. 6, in converter 15, in the voltage region where the boost ratio (VH / VB) is in the vicinity of 1.0, the rate of change of the boost ratio with respect to the change of the duty ratio becomes small. Decreases. Therefore, for a predetermined voltage region AR1 where VH / VB is near 1.0, the duty ratio control of converter 15 is prohibited and system voltage VH is stabilized by upper arm on control.

  For example, voltage region AR1 (hereinafter also referred to as upper arm-on region AR1) is defined by VB ≦ VH ≦ VH + Vα (Vα: a predetermined value). That is, voltage command value VH * of converter 15 is not set in the range of VB <VH * ≦ VB + Vα, but is set to VH * = VB (during upper arm on control) or VH + Vα <VH * ≦ VHmax. . VHmax is a control upper limit value of the system voltage VH.

  FIG. 7 is a flowchart illustrating a control process for setting voltage command value VH * of converter 15. The flowchart shown in FIG. 7 is executed at predetermined control cycles by the control device 50 (VH command generation unit 400).

  Referring to FIG. 7, control device 50 reads the operating point and battery voltage VB of motor generators MG1, MG2 in the current control cycle in step S100. For example, torque command values Tqcom (1), Tqcom (2) set by traveling control, rotation speeds Nm1, Nm2 based on the detection value of rotation angle sensor 28, and battery voltage VB based on the detection value of voltage sensor 10 are To be acquired. For battery voltage VB, a constant value corresponding to the rated value may be fixedly used.

  Further, in step S110, control device 50 calculates optimum voltage Vopt corresponding to system voltage VH at which the total loss Pls is minimized at the operating point read in step S110. As described in Patent Document 1, the optimum voltage Vopt is a voltage at which the estimated value of the total loss Pls is minimized from a plurality of candidate voltages for the system voltage VH using the loss estimation unit 500 shown in FIG. Can be performed by searching. As described above, in step S110, the optimum value (optimum voltage Vopt) of the system voltage VH that can minimize the total loss can be calculated by the same method as in Patent Document 1. However, in the present embodiment, the optimum voltage Vopt may be calculated by any method other than the above.

  When calculating the optimum voltage Vopt (S110), the control device 50 advances the processing to step S120, and determines whether or not the optimum voltage Vopt calculated in step S110 is within the upper arm on area AR1 shown in FIG. To do.

  When the optimum voltage Vopt (S110) is outside the upper arm on-region AR1 (when NO is determined in S120), the control device 50 proceeds to step S130 and uses the optimum voltage Vopt calculated in step S110 as it is. Set to command value VH *. That is, VH * = Vopt is set.

  FIG. 8 shows the characteristics of the total loss in the case where the voltage command value VH * is set in step S130.

  Referring to FIG. 8, in this case, optimum voltage Vopt at which total loss Pls is minimum is located in a higher voltage region than upper arm-on region AR1. Therefore, by setting VH * = Vopt, system voltage VH can be controlled by switching control of switching elements Q1 and Q2 in converter 15 so that total loss Pls is minimized.

  Referring to FIG. 7 again, when optimum voltage Vopt (S110) is within upper arm on area AR1 (when YES is determined in S120), control device 50 proceeds to step S140 to perform upper arm on control. The total loss Pls (VB) when VH = VB applied is calculated using the loss estimation unit 500.

  Further, in step S150, control device 50 uses loss estimation unit 500 to calculate total loss Pls (V1) when system voltage VH is set to predetermined voltage V1.

  Referring to FIG. 6 again, the predetermined voltage V1 is a predetermined voltage outside the upper arm on area AR1. For example, V1 = VB + Vα + Vβ (Vβ: predetermined value) is set. Note that Vβ is preferably as small as possible in consideration of the controllability of the system voltage VH. The predetermined voltage V1 corresponds to a lower limit voltage at which switching control by the converter 15 is possible. Therefore, when voltage command value VH * = V1, converter 15 controls system voltage VH by switching control involving on / off of switching elements Q1, Q2.

  Further, in step S160, the control device 50 compares the total losses Pls (VB) and Pls (V1) calculated in steps S140 and S150. Then, when Pls (VB)> Pls (V1), control device 50 sets voltage command value VH * in step S170.

  FIG. 9 shows the characteristic of the total loss in the case where the voltage command value VH * is set in step S170.

  Referring to FIG. 9, in this case, since optimum voltage Vopt is within upper arm ON range AR1, voltage command value VH * cannot be set to optimum voltage Vopt. On the other hand, comparing the total loss Pls (V1) at the predetermined voltage V1 with the total loss Pls (VB) when the upper arm on control is applied, the total loss Pls (V1) when VH = V1 is Lower than Pls (VB).

  Therefore, in the case of FIG. 9, the total loss Pls can be reduced by controlling the system voltage VH to the predetermined voltage V1 higher than the optimum voltage Vopt rather than applying the upper arm on control. As a result, as shown in FIG. 7, in step S170, the voltage command value VH * is set to the predetermined voltage V1 (VH * = V1).

  On the other hand, when Pls (VB) ≦ Pls (V1), control device 50 sets voltage command value VH * in step S180.

  FIG. 10 shows the characteristic of total loss in the case where the voltage command value VH * is set in step S180.

  Referring to FIG. 10, even in this case, system voltage VH cannot be controlled to optimum voltage Vopt. On the other hand, when the total loss Pls (V1) at the lower limit voltage V1 at which switching control by the converter 15 is possible is compared with the total loss Pls (VB) when the upper arm on control is applied, when the upper arm on control is applied (VH = VB) ) Total loss Pls (VB) is lower than Pls (V1).

  Therefore, in the case of FIG. 10, the total loss Pls can be reduced when the upper arm on control is applied than when the control of the converter 15 is controlled to VH = V1. As a result, as shown in FIG. 7, in step S180, upper arm on control is applied (VH * = VB).

  In the flowchart of FIG. 7, the function of “loss estimation means” is realized by the process of step S110, and the function of “voltage range limiting means” is realized by the process of step S120 (particularly, the process at the time of NO determination). . Further, the function of “first setting means” is realized by the process of step S130, the function of “second setting means” is realized by the process of step S170, and the “third setting means” is realized by the process of step S180. The function is realized.

  As described above, according to the embodiment of the present invention, torque variation of motor generators MG1, MG2 due to variation of system voltage VH can be prevented by providing upper arm on region AR1. Further, even in a case where the system voltage (optimal voltage Vopt) at which the total loss Pls is minimized is located in the upper arm on region AR1, the voltage command value VH * of the converter 15 is prevented so that the power loss of the motor drive system does not become excessive. Can be set appropriately. Thereby, both the stability of the system voltage VH and the improvement of the efficiency of the motor drive control system can be achieved.

  Further, in the embodiment of the present invention, the electric motor drive control system mounted on the hybrid vehicle is representatively exemplified, but the application of the present invention is not limited to such a case. That is, the motor drive system according to the present invention can also be applied to an electric motor drive control system mounted on an electric vehicle other than a hybrid vehicle represented by an electric vehicle. In addition, in the case of an electric motor drive control system including a converter capable of variably controlling DC voltage, the number and type of motor generators (or electric motors / generators) to be driven are controlled by the motor generators (electric motors). The present invention can be applied without limiting the load to be applied.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  5, 6, 7 Power line, 10, 13 Voltage sensor, 11, 27 Current sensor, 12 Temperature sensor, 15 Converter, 20, 30 Inverter, 22, 24, 26, 32, 34, 36 Each phase arm (inverter), 28 Rotation angle sensor, 50 control device, 100 hybrid vehicle, 110 engine, 112 rotation speed sensor (engine), 120 power split mechanism, 125 output shaft, 130 speed reducer, 140 drive shaft, 150 drive wheel, 300 operation command generator, 350 engine control unit, 400 VH command generation unit, 410 converter control unit, 420 MG control unit, 500 loss estimation unit, 550 battery loss estimation unit, 555, 565, 575 loss map, 560 converter loss estimation unit, 570 inverter loss estimation Part, 580 MG loss estimation part, 590 Arithmetic unit, AR1 upper arm on area, Acc accelerator operation amount, B running battery, Brk brake operation amount, C0, C1 smoothing capacitor, D1, D2, D11 to D16, D21 to D26 anti-parallel diode, IB battery current, L1 reactor MCRT (1), MCRT (2) Motor current, MG1, MG2 Motor generator, N1, N2 Neutral point, Ne Target engine speed, Nm1, Nm2 Speed (motor generator), Plb Battery loss, Plcv converter loss, Plib1, Priv2 Inverter loss, Pls total loss (motor drive control system), Pmg1, Pmg2 MG loss, Q1, Q2, Q11-Q16, Q21-Q26 Power semiconductor switching elements, S1, S2, S11-S16, S21-S 6 Control signal, SP vehicle speed, TB battery temperature, Te * target engine torque, Tqcom (1), Tqcom (2) torque command value, U1, U2, V1, V2, W1, W2 coil winding, V1 predetermined voltage (converter Lower limit voltage of switching control), VB battery voltage, VH DC voltage (system voltage), VH * voltage command value (system voltage).

Claims (1)

A power storage device;
A converter that converts the voltage of the power storage device into a DC voltage having a step-up ratio of 1.0 or more according to a voltage command value and outputs the DC voltage to a DC power supply wiring;
An inverter that performs power conversion between the DC voltage of the DC power supply wiring and the AC voltage that drives the electric motor by a plurality of switching elements so that the electric motor operates according to an operation command;
Voltage setting means for setting the voltage command value of the converter,
The voltage setting means includes
Voltage range limiting means for prohibiting setting the voltage command value within a predetermined voltage range in which the step-up ratio is larger than 1.0 and smaller than a predetermined value;
Based on a preset loss characteristic, in the current operating state of the motor, the direct current at which the estimated value of total power loss including power loss in the power storage device, the converter, the inverter, and the motor is minimized A loss estimation means for obtaining an optimum voltage which is a voltage;
First setting means for setting the voltage command value to the optimum voltage when the optimum voltage is outside the predetermined voltage range;
When the optimum voltage is within the predetermined voltage range, the estimated value of the total power loss when the step-up ratio is 1.0 is the predetermined voltage on the higher voltage side than the predetermined voltage range. Second setting means for setting the voltage command value to the predetermined voltage when higher than the estimated value of the total power loss when
When the optimum voltage is within the predetermined voltage range, the estimated value of the total power loss when the step-up ratio is 1.0 is the total power loss when the DC voltage is the predetermined voltage. And a third setting means for setting the voltage command value so that the step-up ratio becomes 1.0 when the ratio is lower than the estimated value.

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