JP2012249383A - Control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress overheating of electronic components stored in a power control unit (PCU) and reduce noise generated at the PCU when controlling the PCU by pulse width modulation (PWM) control.SOLUTION: A control apparatus 200 for controlling a PCU for driving a motor by PWM control, includes a temperature information acquisition unit 210, and a random carrier control unit 220. The temperature information acquisition unit 210 acquires a temperature THL of a reactor and a temperature THC1 of a filter capacitor, which are stored in the PCU. The random carrier control unit 220 executes random carrier control when both of the temperatures THC1 and THL are less than corresponding threshold temperatures A and B, respectively. Meanwhile, the random carrier control unit 220 prohibits the execution of the random carrier control when at least one of the temperatures THC1 and THL is equal to or greater than at least one of the corresponding threshold temperatures A and B.

Description

  The present invention relates to control of a power controller, and more particularly to pulse width modulation (hereinafter also referred to as “PWM”) control of a power controller.

  Japanese Patent Laid-Open No. 2004-48844 (Patent Document 1) discloses that when a power controller for driving a motor (such as an inverter or a converter) is controlled by PWM control, the carrier frequency used for PWM control is low during normal driving. A technique is disclosed that suppresses sensory noise that a user feels when riding while improving fuel efficiency by changing to a higher value at low vehicle speed while maintaining the value.

JP 2004-48844 A

  However, if the carrier frequency is set to a relatively low value, the ripple width of the current flowing through the power controller may increase, and as a result, heat generated by electronic components (for example, a reactor and a filter capacitor) accommodated in the power controller is increased. May increase.

  The present invention has been made to solve the above-described problems, and its purpose is to suppress overheating of electronic components housed in the power controller when the power controller is controlled by pulse width modulation control. However, it is to reduce the noise generated in the power controller.

  A control device according to the present invention is a control device that controls a power controller for driving a motor by pulse width modulation control, an acquisition unit that acquires information about the temperature of an electronic component housed in the power controller, and a pulse And a variation control unit that performs variation control for arbitrarily varying a carrier frequency used for width modulation control within a predetermined range. The variation control unit prohibits execution of variation control or changes the variation range of the carrier frequency according to information on the temperature of the electronic component.

  Preferably, the temperature information is a detected temperature or an estimated temperature of the electronic component. The fluctuation control unit executes fluctuation control when the detected temperature or estimated temperature is lower than the reference temperature, and prohibits fluctuation control when the detected temperature or estimated temperature is equal to or higher than the reference temperature.

  Preferably, the temperature information is a detected temperature or an estimated temperature of the electronic component. The variation control unit narrows the variation range when the detected temperature or the estimated temperature is equal to or higher than the reference temperature than the variation range when the detected temperature or the estimated temperature is lower than the reference temperature.

  Preferably, the temperature-related information is an electronic component load correlated with the temperature of the electronic component. The fluctuation control unit sets a reference time according to the load, executes the fluctuation control when the load duration is less than the reference time, and prohibits the fluctuation control when the load duration is equal to or longer than the reference time. .

  Preferably, the temperature-related information is an electronic component load correlated with the temperature of the electronic component. The fluctuation control unit sets a reference time according to the load, and narrows the fluctuation width when the load duration is longer than the reference time than the fluctuation width when the load duration is less than the reference time.

  Preferably, the load includes at least one of an electric current and voltage of the electronic component, a cooling water temperature of the electronic component, a carrier frequency, and an energization time of the electronic component.

  ADVANTAGE OF THE INVENTION According to this invention, when controlling a power controller by pulse width modulation control, the noise which arises in a power controller can be reduced, suppressing the overheating of the electronic component accommodated in a power controller.

1 is an overall configuration diagram of a motor drive control system. It is a wave form diagram of the signal used for PWM control. It is a functional block diagram of a control device. It is a flowchart (the 1) which shows the process sequence of a control apparatus. It is a flowchart (the 2) which shows the process sequence of a control apparatus. It is a figure which shows an example of a temperature estimation map.

  Embodiments of the present invention will be described below 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.

[Embodiment 1]
FIG. 1 is an overall configuration diagram of a motor drive control system 1 to which a control device according to the present embodiment is applied. In the present embodiment, the case where the target of PWM control by the control device is an inverter will be described. However, the control target of the present invention is not limited to the inverter, and is a general power controller that can be controlled by PWM control (for example, Converter).

  Referring to FIG. 1, motor drive control system 1 includes a DC power supply B, a motor M1, a power controller (power control unit, hereinafter referred to as “PCU”) 100, and a control device 200. Prepare.

  The DC power supply B is typically constituted by a secondary battery such as nickel metal hydride or lithium ion, or a power storage device such as an electric double layer capacitor.

  The motor M1 is an AC motor for generating torque for driving drive wheels of an electric vehicle (referred to as a vehicle that generates vehicle driving force by electric energy such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle). It is. Typically, the motor M1 is a permanent magnet type synchronous motor provided with three coils of three phases (U, V, W phase). The motor M1 may be configured to have a generator function.

  Inside PCU 100, converter 110, filter capacitors C0 and C1, inverter 120, and cooling device 130 are accommodated.

  Converter 110 includes a reactor LA1, switching elements Q1, Q2, and diodes D1, D2. Reactor LA1 is provided between power line 6 connected to the positive terminal of DC power supply B and the connection node of switching elements Q1 and Q2. Switching elements Q1 and Q2 are connected in series between power line 7 and ground line 5. Switching elements Q1 and Q2 are turned on / off by switching control signals S1 and S2 from control device 200. Converter 110 performs voltage conversion between DC power supply B and inverter 120 by a switching operation in response to switching control signals S1 and S2.

  Filter capacitor C <b> 1 is connected between power line 6 and ground line 5, and smoothes the voltage between power line 6 and ground line 5. Filter capacitor C 0 is connected between power line 7 and ground line 5, and smoothes the voltage between power line 7 and ground line 5.

  Inverter 120 includes U-phase upper and lower arms 15, V-phase upper and lower arms 16, and W-phase upper and lower arms 17. The upper and lower arms of each phase are provided in parallel between the power line 7 and the ground line 5. That is, the U-phase upper and lower arms 15 are composed of switching elements Q3 and Q4, the V-phase upper and lower arms 16 are composed of switching elements Q5 and Q6, and the W-phase upper and lower arms 17 are composed of switching elements Q7 and Q8. Further, diodes D3 to D8 are connected in antiparallel to switching elements Q3 to Q8, respectively. The other end of each phase coil of the motor M1 is connected to an intermediate point of the switching elements of the upper and lower arms 15 to 17 of each phase. Switching elements Q3 to Q8 are turned on / off by switching control signals S3 to S8 from control device 200.

  Inverter 120 converts a DC voltage into an AC voltage and outputs a positive torque by a switching operation in response to switching control signals S3 to S8 during powering control of motor M1 (when the electric vehicle is running). The motor M1 is driven. Further, the inverter 120 converts the AC voltage generated by the motor M1 into a DC voltage by switching operation in response to the switching control signals S3 to S8 during regenerative control of the motor M1 (when regenerative braking of the electric vehicle). The converted DC voltage is supplied to the converter 110 via the filter capacitor C0.

  The cooling device 130 cools electronic components (components constituting the converter 110 and the inverter 120) accommodated inside the PCU 100 by cooling water flowing inside.

  Further, the motor drive control system 1 includes current sensors 11, 12, 19, voltage sensors 10, 14, 17, temperature sensors 13, 15, 16, 18, and a rotation angle sensor (resolver) 20.

  The current sensor 11 detects a current Ib flowing through the DC power source B. Current sensor 12 detects current IL flowing through reactor LA1. The current sensor 19 detects a current Im flowing through the motor M1. Since the sum of the instantaneous values of the three-phase currents is zero, the current sensor 19 can be arranged to detect phase currents for two phases (for example, V-phase current and W-phase current as shown in FIG. 1). It ’s enough. The voltage sensor 10 detects a voltage Vb across the DC power supply B (hereinafter also simply referred to as “voltage Vb”). The voltage sensor 14 detects a voltage VL across the filter capacitor C1 (hereinafter also simply referred to as “voltage VL”). The voltage sensor 17 detects a voltage VH across the filter capacitor C0 (hereinafter also simply referred to as “voltage VH”). The temperature sensor 13 detects the temperature THC1 (capacitor temperature THC1) of the filter capacitor C1. Temperature sensor 15 detects temperature THL of reactor LA1 (reactor temperature THL). The temperature sensor 16 detects the temperature THC0 (capacitor temperature THC0) of the filter capacitor C0. The temperature sensor 18 detects the temperature THW (cooling water temperature THW) of the cooling water flowing inside the cooling device 130. Each of these sensors outputs a detection result to the control device 200.

  The control device 200 includes a CPU (Central Processing Unit) (not shown) and an electronic control unit (ECU: Electronic Control Unit) with a built-in memory, and executes predetermined arithmetic processing based on information and programs stored in the memory. By doing so, the operation of the motor drive control system 1 is controlled.

  FIG. 2 is a waveform diagram of signals used for PWM control. The PWM control of the inverter 120 will be described with reference to FIG. As shown in FIG. 2, in PWM control, pulse width modulation as a pseudo sine wave voltage is performed by controlling on / off of switching elements of each phase of the inverter 120 based on a voltage comparison between the carrier signal CR and the phase voltage command 170. A voltage 180 is applied to each phase of the motor M1. Therefore, the number of switching operations per unit time of each switching element (hereinafter also referred to as “switching frequency”) depends on the frequency of the carrier signal CR (hereinafter also referred to as “carrier frequency f”). The carrier signal CR can be configured by a triangular wave or a sawtooth wave. FIG. 2 illustrates a triangular wave.

  Noise and loss (switching loss) occur in the inverter 120 due to the switching operation during the PWM control. When the carrier frequency f is high, noise is small but loss is large. On the other hand, when the carrier frequency f is low, the loss is small but the noise is large. From the viewpoint of energy efficiency, it is desirable to set the carrier frequency f to a low value with little loss, but there is a problem that noise increases.

  In view of such a problem, control device 200 according to the present embodiment sets a frequency (center carrier) according to the operating state of motor M1, and does not fix carrier frequency f but a predetermined range centered on the center carrier. "Random carrier control" that is arbitrarily changed within the range is executed. Thus, by changing the carrier frequency f by random carrier control, noise generated in the inverter 120 during PWM control can be reduced.

  However, this random carrier control also causes the following trade-off. As described above, in the random carrier control, the carrier frequency f is changed around the center carrier. Therefore, during random carrier control, a timing at which a carrier frequency f lower than the center carrier is used occurs. Due to this influence, the ripple width of the current IL flowing through the reactor LA1 becomes large, and there is a possibility that the heat generation amount of the reactor LA1 and the filter capacitor C1 becomes large.

  In order to avoid such a problem, control device 200 performs control for suppressing overheating of PCU 100 during random carrier control.

  FIG. 3 is a functional block diagram of a part of the control device 200 relating to PCU overheating suppression during random carrier control. Each functional block shown in FIG. 3 may be realized by hardware or software.

  The control device 200 includes a temperature information acquisition unit 210 and a random carrier control unit 220.

  The temperature information acquisition unit 210 acquires the output of a temperature sensor that detects the temperature of a component to be overheat protected (hereinafter referred to as “overheat protection target component”) among the electronic components housed in the PCU 100. In addition, in the following description, the case where the reactor LA1 and the filter capacitor C1 are overheat protection target parts will be described as an example. In addition, components other than these may be contained in overheat protection object components.

  The temperature information acquisition unit 210 acquires the capacitor temperature THC1 and the reactor temperature THL from the temperature sensors 13 and 15, respectively.

  The random carrier control unit 220 determines whether or not to execute random carrier control according to the capacitor temperature THC1 and the reactor temperature THL. The random carrier control unit 220 executes random carrier control when both the capacitor temperature THC1 and the reactor temperature THL are lower than the corresponding threshold temperatures A and B, respectively. That is, as described above, the random carrier control unit 220 sets the center carrier according to the operation state of the motor M1, and arbitrarily varies the carrier frequency f within a predetermined range around the center carrier. Thereby, noise generated in the inverter 120 is reduced.

  On the other hand, when at least one of capacitor temperature THC1 and reactor temperature THL is equal to or higher than the corresponding threshold temperatures A and B, random carrier control unit 220 prohibits execution of random carrier control. In this case, the random carrier control unit 220 sets the center carrier according to the operating state of the motor M1, and fixes the carrier frequency f to the center carrier. Thereby, the timing at which the carrier frequency f lower than the center carrier is used does not occur, the ripple width of the current IL is reduced, and the heat generation of the reactor LA1 and the filter capacitor C1 is suppressed. As a result, overheating of reactor LA1 and filter capacitor C1 can be suppressed.

  FIG. 4 is a flowchart showing a processing procedure of the control device 200 for realizing the above-described function. The flowchart shown in FIG. 4 is repeatedly executed at a predetermined cycle.

  In step (hereinafter, step is abbreviated as “S”) 10, control device 200 determines whether or not reactor temperature THL and capacitor temperature THC1 are equal to or higher than threshold temperatures A and B, respectively.

  If THL <A and THC1 <B (NO in S10), control device 200 moves the process to S13 and executes random carrier control.

  On the other hand, if THL ≧ A or THC1 ≧ B (YES in S10), control device 200 moves the process to S11 and prohibits execution of random carrier control.

  After prohibiting random carrier control, control device 200 moves the process to S12, and determines whether or not reactor temperature THL and capacitor temperature THC1 are equal to or lower than the corresponding threshold temperatures C and D, respectively. The “threshold temperature C” that is compared with the reactor temperature THL in S12 is different from the “threshold temperature A” in S10 because the hysteresis is between “threshold temperature C” and “threshold temperature A”. It is for providing. Therefore, the threshold temperature C is set to a value lower than the threshold temperature A by a predetermined temperature. For the same reason, the “threshold temperature D” compared with the capacitor temperature THC1 is set to a value lower than the “threshold temperature B” in S10 by a predetermined temperature. The “threshold temperature C” may be the same value as the “threshold temperature A”. The “threshold temperature D” may be the same value as the “threshold temperature B”.

  If THL> C or THC1> D (NO in S12), control device 200 returns the process to S11 and continues prohibiting random carrier control.

  On the other hand, if THL ≦ C and THC1 ≦ D (YES in S12), control device 200 moves the process to S13, cancels the prohibition of random carrier control, and executes random carrier control.

  As described above, the control device 200 according to the present embodiment does not fix the carrier frequency f but reduces the noise generated in the inverter 120 at the time of PWM control arbitrarily within a predetermined width around the center carrier. Random carrier control to be changed is executed. At this time, in consideration of the fact that the amount of heat generated by reactor LA1 and filter capacitor C1 increases due to random carrier control, control device 200 considers that reactor temperature THL and capacitor temperature THC1 exceed the respective threshold temperatures. The generation of the reactor LA1 and the filter capacitor C1 is suppressed by prohibiting the execution of random carrier control until the reactor temperature THL and the capacitor temperature THC1 fall below the respective threshold temperatures. As a result, when the inverter 120 is controlled by PWM control, noise generated in the inverter 120 can be reduced while suppressing overheating of the reactor LA1 and the filter capacitor C1 accommodated in the PCU 100.

  In the present embodiment, the case where the execution of the random carrier control itself is prohibited according to the temperature of the overheat protection target component has been described, but instead of or in addition to this, the fluctuation range of the carrier frequency f is changed. You may deform | transform into. In this case, the lower limit value of the variation range of the carrier frequency f is increased in accordance with the temperature of the overheat protection target component by narrowing the variation range of the carrier frequency f in accordance with the temperature of the overheat protection target component. That's fine.

[Embodiment 2]
In the above-described first embodiment, the temperature of the overheat protection target component is detected by the temperature sensor.

  On the other hand, in this Embodiment 2, in order to deal with an electronic component not provided with a temperature sensor, random carrier control is prohibited based on the result of estimating the temperature of the electronic component from the vehicle load. Since other structures, functions, and processes are the same as those in the first embodiment, detailed description thereof will not be repeated here.

FIG. 5 is a flowchart showing a processing procedure of the control device 200.
In S20, control device 200 determines whether or not each vehicle load continues for a reference time determined by the temperature estimation map.

  Here, as the vehicle load, a physical quantity having a correlation with the temperature of the overheat protection target component can be selected. For example, when the overheat protection target component is the reactor LA1 or the filter capacitor C1, the vehicle load may be set to the average values of the current IL, the voltage VH, the coolant temperature THW, the carrier frequency f, and the like. In addition, you may put the electricity supply time of overheat protection object components in a vehicle load. The temperature estimation map is a map in which the correspondence between the vehicle load and the reference time is stored in advance. The reference time is a value obtained by an experiment or the like that is predicted to cause the temperature of the overheat protection target component to reach the threshold temperature when a certain vehicle load continues.

  FIG. 6 is an example of a temperature estimation map. FIG. 6 illustrates the case where the reference time is set using the current IL, voltage VL, and cooling water temperature THW as parameters. Such a temperature estimation map is created in advance for each overheat protection target component and stored in the memory.

  Returning to FIG. 5, in S20, control device 200 monitors each vehicle load and its application time, reads a reference time corresponding to each vehicle load with reference to the temperature estimation map, and each vehicle load has a temperature. It is determined whether or not the duration exceeds the reference time determined by the estimation map. In addition, the control apparatus 200 performs such determination for every overheat protection object component.

  When each vehicle load does not continue for the reference time or longer (NO in S20), control device 200 assumes that the estimated temperature of the overheat protection target component is lower than the threshold temperature, and moves the process to S23 to perform random carrier control. Execute.

  On the other hand, when each vehicle load continues for the reference time or longer (YES in S20), control device 200 assumes that the estimated temperature of the overheat protection target component is equal to or higher than the threshold temperature, and moves the process to S21 for random carrier control. Is prohibited.

  After prohibiting the random carrier control, the control device 200 moves the process to S22, and determines whether or not each vehicle load has fallen below the reference time determined by the temperature estimation map.

  If each vehicle load does not fall below the reference time (NO in S22), control device 200 returns the process to S21 and continues prohibiting random carrier control.

  On the other hand, when each vehicle load falls below the reference time (YES in S22), control device 200 moves the process to S23, cancels the prohibition of random carrier control, and executes random carrier control.

  As described above, in the present embodiment, random carrier control is prohibited in accordance with the temperature of electronic components estimated from each vehicle load (duration of high load). For this reason, it is possible to deal with an electronic component without a temperature sensor.

  In the present embodiment, it may be modified to change the fluctuation range of the carrier frequency f instead of prohibiting the execution of random carrier control.

  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.

  DESCRIPTION OF SYMBOLS 1 Motor drive control system, 5 Ground wire, 6,7 Power line, 10, 14, 17 Voltage sensor, 11, 12, 19 Current sensor, 13, 15, 16, 18 Temperature sensor, 15-17 Upper / lower arm of each phase, 100 PCU, 110 converter, 120 inverter, 130 cooling device, 200 control device, 210 temperature information acquisition unit, 220 random carrier control unit.

Claims (6)

A control device for controlling a power controller for driving a motor by pulse width modulation control,
An acquisition unit for acquiring information about the temperature of the electronic component housed in the power controller;
A fluctuation control unit for performing fluctuation control for arbitrarily changing the carrier frequency used for the pulse width modulation control within a predetermined range;
The fluctuation control unit is a control device that prohibits execution of the fluctuation control or changes a fluctuation range of the carrier frequency according to information on the temperature of the electronic component. The information on the temperature is a detection temperature or an estimated temperature of the electronic component,
The fluctuation control unit executes the fluctuation control when the detected temperature or the estimated temperature is lower than a reference temperature, and prohibits the fluctuation control when the detected temperature or the estimated temperature is equal to or higher than the reference temperature. The control device according to claim 1. The information on the temperature is a detection temperature or an estimated temperature of the electronic component,
The fluctuation control unit narrows the fluctuation width when the detected temperature or the estimated temperature is equal to or higher than the reference temperature than the fluctuation width when the detected temperature or the estimated temperature is lower than a reference temperature. The control device according to claim 1. The information on the temperature is a load of the electronic component correlated with the temperature of the electronic component,
The variation control unit sets a reference time according to the load, executes the variation control when the duration of the load is less than the reference time, and the duration of the load is equal to or longer than the reference time. The control device according to claim 1, wherein in the case, the variation control is prohibited. The information on the temperature is a load of the electronic component correlated with the temperature of the electronic component,
The variation control unit sets a reference time according to the load, and when the duration of the load is equal to or more than the reference time than the variation when the duration of the load is less than the reference time The control device according to claim 1, wherein the fluctuation range is narrowed.   The control device according to claim 4 or 5, wherein the load includes at least one of a current and a voltage of the electronic component, a cooling water temperature of the electronic component, the carrier frequency, and an energization time of the electronic component.

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