JP2016046989A - Voltage converter control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage converter control device capable of detecting an abnormality in a voltage converter without being influenced by error or variations in a voltage sensor.SOLUTION: An abnormality detection part of the voltage converter control device detects the abnormality in the voltage converter by comparing (S15) a differential (Δ integration term) between values of integration terms at power running and regenerative times, the differential being obtained by feedback calculation using a boost control part, with a sum (α+β) of dead time equivalent duties at the power running and regenerative times. Other values than a dead time equivalent component are common for the integration terms at the power running and regenerative times, such that influences caused by error or variations in the voltage sensor are cancelled by calculating the differential between the values of the integration terms at the power running and regenerative times. The abnormality in the voltage converter therefore can be detected without being influenced by the error or variations in the voltage sensor by comparing the differential with the sum of the dead time equivalent duties. Thus, the occurrence of erroneous detection or omission in abnormality detection can be prevented.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a voltage converter control device that controls a voltage converter.

  2. Description of the Related Art Conventionally, a device for detecting an abnormality of an input voltage sensor or an output voltage sensor in a control device for a voltage converter that is provided between a battery and a load circuit and converts a voltage by operation of switching elements on a high potential side and a low potential side. It has been known.

  For example, the apparatus disclosed in Patent Document 1 is based on the battery voltage V1 detected by the input voltage sensor, the inverter input voltage V2 detected by the output voltage sensor, and the duty of the voltage converter, and the difference voltage ΔV (= V1−V2). Xduty) is calculated, and when this difference voltage ΔV is larger than the abnormality determination threshold, it is determined that any one of the voltage sensors has failed.

Japanese Patent No. 3632657

  In the prior art of Patent Document 1, since abnormality detection is performed using both the detection values of the input voltage sensor and the output voltage sensor, if an error or variation between the two voltage sensors is taken into consideration, the abnormality determination value is set. It can be difficult. As a result, there is a possibility that false detection that erroneously determines that the voltage sensor is normal but that it is abnormal or detection omission that fails to detect the abnormality may occur.

  The present invention was created in view of the above points, and an object of the present invention is to provide a voltage converter control device capable of detecting an abnormality of a voltage converter without being affected by errors or variations in the voltage sensor. It is in.

  The voltage converter control device of the present invention is provided between a battery and a load circuit, and is a reactor capable of storing and discharging electric energy, and a high potential that repeatedly stores and discharges electric energy in the reactor by alternately turning on and off. The voltage converter includes a side switching element and a low potential side switching element, and is applied to a voltage converter that converts an input voltage (Vin) on the battery side and an output voltage (Vsys) on the load circuit side in a power running direction and a regeneration direction. The

The voltage converter control device includes a boost control unit and an abnormality detection unit.
The voltage control unit calculates the duty, which is the on-time ratio with respect to the switching cycle of the high potential side switching element, based on the ratio between the output voltage command value (Vsys ^* ) that is the target value for the output voltage and the input voltage. Addition and subtraction of “feed-forward term” and “feedback term” including proportional term and integral term calculated so that the detected value of output voltage matches the output voltage command value, and output to the voltage converter , Calculated based on the difference value of the integral term calculated in a predetermined integration period at the time of power running and regeneration, the dead time setting value of the voltage conversion unit and the carrier cycle at the time of power running and regeneration, and “duty equivalent to dead time” Is detected by comparing the absolute value of "

  In the present invention, the influence of the error or variation of the voltage sensor is absorbed in the integral term by feedback control that corrects the output voltage to be the command value. Here, since the integral term for power running and regeneration is the same value other than the dead time, calculating the differential value of the integral term for power running and regeneration can affect the error and variation of the voltage sensor. Will be countered. Therefore, by comparing the difference value with the sum of the absolute values of the dead time equivalent duty, the abnormality of the voltage converter can be detected without being affected by the error or variation of the voltage sensor. Therefore, it is possible to prevent erroneous detection and detection omission in abnormality detection.

  Preferably, when detecting an abnormality of the voltage converter, the abnormality detection unit of the present invention further includes “comparison between the value of the integral term during power running and the dead time equivalent duty during power running” or “integration during regeneration”. At least one of “comparison between term value and dead time equivalent duty during regeneration” is executed. More preferably, both are performed.

  Thereby, it is possible to roughly classify whether the failed part is a part used for powering, a part used for regeneration, or a part used for both powering and regeneration. And, for example, when the present invention is used in a system for driving a motor generator of a hybrid vehicle, from a fail-safe viewpoint, using only components that operate normally, and performing only regenerative operation when there is a power running abnormality, By performing only the power running operation when the regeneration is abnormal, it is possible to realize the retreat travel at the time of abnormality. Moreover, since it is only necessary to replace only the relevant parts when repairing the voltage converter, the repair cost can be reduced as compared with the case where all the parts are replaced.

1 is a schematic configuration diagram of a system to which a voltage converter control device according to an embodiment of the present invention is applied. It is a control block diagram of the voltage converter control apparatus by embodiment of this invention. It is a schematic diagram which shows the electric current which flows into a voltage converter at the time of power running. It is a time chart explaining the dead time at the time of power running. It is a schematic diagram which shows the electric current which flows into a voltage converter at the time of regeneration. It is a time chart explaining the dead time at the time of regeneration. It is a figure which shows the relationship between the value of the integral term at the time of power running / regeneration, and an abnormal area | region. It is a figure which shows the relationship between instruction | command duty at the time of power running / regeneration, and real duty. It is a flowchart of the abnormality detection process by 1st Embodiment of this invention. It is a flowchart of the abnormal region specific process by 2nd Embodiment of this invention.

Embodiments of a voltage converter control device according to the present invention will be described below with reference to the drawings.
First, a configuration common to a plurality of embodiments will be described. Hereinafter, “the present embodiment” includes first and second embodiments described later. The voltage converter control device of the present embodiment is applied to, for example, a voltage converter of a system that drives a motor generator that is a power source of a hybrid vehicle or an electric vehicle.

[Overall configuration of voltage converter]
The overall configuration of the system including the voltage converter will be described with reference to FIG.
As shown in FIG. 1, the voltage converter 20 is provided between the battery 1 and an inverter 7 as a “load circuit” that drives the motor generator 8, and the input voltage Vin on the battery 1 side and the inverter 7 side This is a device for converting the output voltage Vsys. In particular, the voltage converter 20 of the present embodiment is a boost converter that boosts the input voltage Vin and outputs the boosted voltage to the inverter 7.

First, the system configuration outside the range of the voltage converter 20 will be described.
The battery 1 is a direct current power source configured by a chargeable / dischargeable power storage device such as nickel hydride or lithium ion. An electric double layer capacitor or the like is also included in one embodiment of the battery 1.

The inverter 7 is composed of six switching elements that are bridge-connected, and the system voltage Vsys generated by the voltage converter 20 is applied. The inverter 7 converts the DC power into three-phase AC power and supplies it to the motor generator 8 when the switching element of each phase is turned on / off by PWM control or phase control.
The motor generator 8 is, for example, a permanent magnet type synchronous three-phase AC motor. The motor generator 8 is a motor generator (denoted as “MG” in the figure) mounted on a hybrid vehicle or an electric vehicle, and is an electric motor that generates torque for driving drive wheels via a transmission or the like by a power running operation. And a function as a generator that recovers energy by power generation from torque transmitted from the engine and driving wheels.

The vehicle control circuit 40 calculates a torque command value for the motor generator 8 based on signals such as an accelerator signal, a brake signal, a shift signal, and a vehicle speed signal (not shown). Further, based on the torque command value and the rotation speed of the motor generator 8, an output voltage command value Vsys ^* which is a target value for the output voltage Vsys of the voltage converter 20 is calculated and commanded to the voltage converter control device 50.

Based on the input voltage Vin, output voltage Vsys, output voltage command value Vsys ^{*, and the} like of the voltage converter 20, the voltage converter control device 50 calculates a duty command value that is an on / off time ratio with respect to the switching cycle of the switching elements 23 and 24. This is a device that outputs to the booster 22 of the voltage converter 20, and the detailed configuration will be described later.
In another embodiment, the output voltage command value Vsys ^* calculated by the vehicle control circuit 40 is not acquired by the voltage converter control device 50, but the output voltage command value Vsys ^* is calculated inside the voltage converter control device 50. You may do it.

Next, the configuration of the voltage converter 20 will be described. The voltage converter 20 includes a reactor 21 and a booster 22 as a “voltage converter”.
Reactor 21 can store and release electric energy due to an induced voltage generated with a change in current.

  The step-up unit 22 includes two switching elements 23 and 24 connected in series, and freewheeling diodes 25 and 26 connected in parallel to the switching elements 23 and 24. The high potential side switching element 23 is connected between the intermediate point N that is the output end of the reactor 21 and the high potential line Lp of the inverter 7, and the low potential side switching element 24 is connected to the intermediate point N and the low potential of the inverter 7. It is connected between the line Lg. The free-wheeling diodes 25 and 26 are provided in a direction that allows current from the low potential side to the high potential side.

The high potential side switching element 23 and the low potential side switching element 24 are turned on and off alternately and complementarily in response to a duty command from the voltage converter controller 50.
In this specification, “on-duty command value indicating the on-time ratio with respect to the switching period of the high potential side switching element 23” is defined as “duty”. Hereinafter, when “duty” is written in English letters, it means “on-duty command value of the high potential side switching element 23”. Also, duty is defined as a dimensionless number between 0 and 1, not in [%] units.

  If the dead time is ignored, the on-duty command value of the low potential side switching element 24 is described as “1-duty”. However, in general, in order to prevent a short circuit between the high potential line Lp and the low potential line Lg in the boosting unit 22, a dead time for simultaneously turning off both the switching elements 23 and 24 is set. Moreover, in the present invention, since dead time is treated as an important matter, it is not appropriate to ignore it. Therefore, in FIG. 1, parentheses such as (duty) and (1-duty) are given in the sense of reference description.

  During power running, when the high-potential side switching element 23 is off and the low-potential side switching element 24 is on, energy is accumulated by a current flowing from the battery 1 to the reactor 21. When the high potential side switching element 23 is on and the low potential side switching element 24 is off, the energy accumulated in the reactor 21 is released, so that the output voltage Vsys in which the induced voltage is superimposed on the input voltage Vin is generated. It is output to the inverter 7 side.

During regeneration, when the high potential side switching element 23 is on and the low potential side switching element 24 is off, the power on the inverter 7 side is regenerated to the battery 1. When the high potential side switching element 23 is off and the low potential side switching element 24 is on, regeneration from the inverter 7 side is interrupted.
During power running and regeneration, the voltage converted by the voltage converter 20 is controlled to a desired value by turning on and off the switching elements 23 and 24 based on the duty calculated by the voltage converter control device 50.

In addition to the above, a filter capacitor 27 for removing power supply noise from the battery 1 is provided on the input side of the voltage converter 20. The input voltage sensor 31 detects the input voltage Vin. A smoothing capacitor 28 that smoothes the output voltage Vsys to the inverter 7 is provided on the output side of the voltage converter 20. The output voltage sensor 32 detects the output voltage Vsys.
The input voltage sensor value Vin detected by the input voltage sensor 31 and the output voltage sensor value Vsys detected by the output voltage sensor 32 are input to the voltage converter control device 50.

[Configuration of voltage converter controller]
Next, the configuration of the voltage converter control device 50 will be described with reference to FIG. The voltage converter control device 50 is configured by a microcomputer or the like, and includes a CPU, a ROM, an I / O (not shown), a bus line connecting these configurations, and the like. The voltage converter control device 50 executes control by software processing by executing a program stored in advance by the CPU or by hardware processing by a dedicated electronic circuit.

The voltage converter control device 50 includes a boost control unit 55 as a “voltage control unit” and an abnormality detection unit 60 that detects an abnormality of the voltage converter 20.
The boost control unit 55 includes a feedback subtractor 51, a PI controller 52, a feedforward calculation unit 53, and a duty subtractor 54.
The feedback subtractor 51 calculates a deviation ΔVsys between the output voltage command value Vsys ^* and the output voltage Vsys. The PI controller 52 calculates the feedback term duty_fb of the duty by a proportional integration calculation so that the deviation ΔVsys of the output voltage converges to zero.

The feedback term duty_fb includes a proportional term duty_P and an integral term duty_I. The proportional term duty_P is proportional to the instantaneous deviation ΔVsys between the output voltage Vsys and the command value Vsys ^*, and changes following the command value Vsys ^* that changes greatly due to a sudden change in the driving state of the vehicle, for example. The integral term duty_I is calculated by accumulating the deviation ΔVsys between the output voltage Vsys and the command value Vsys ^* over a predetermined integration period. In other embodiments, the feedback term may further include a differential term.
In the present embodiment, the proportional term duty_P associated with a sudden change in the operating state or the like is not considered, and attention is paid mainly to the integral term duty_I that reflects the accumulated value of the output voltage deviation ΔVsys due to the abnormality of the voltage converter 20. Further, both the integral term during power running (“integral term_power running”) and the integral term during regeneration (“integral term_regenerative”) are used for control.

The feedforward calculation unit 53 calculates the feedforward term duty_ff of the duty based on the ratio between the input voltage Vin and the output voltage command value Vsys ^* .
The duty subtractor 54 adds and subtracts the feedforward term duty_ff and the feedback term duty_fb, and outputs the result to the booster 22 as “duty”. In the present embodiment, a value obtained by subtracting the feedback term duty_fb from the feedforward term duty_ff is defined as duty. Therefore, the larger the value of the feedback term duty_fb to be subtracted, the smaller the output duty. In addition, you may determine the positive / negative definition of each term, and the distinction of addition or subtraction by it according to embodiment suitably.

  By the way, there is a possibility that the switching elements 23 and 24, the freewheeling diodes 25 and 26, or the voltage sensors 31 and 32 constituting the voltage converter 20 may fail. If these elements or sensors fail, the control of the boost control unit 55 may become unstable or the control may not be established. Therefore, the voltage converter control device 50 of the present invention includes an abnormality detection unit 60 that detects such an abnormality of the voltage converter 20.

The abnormality detection unit 60 includes a dead time conversion unit 61, a reversing unit 62, a power running / regeneration determination unit 63, a switching unit 64, and an abnormality determination unit 65.
The dead time conversion unit 61 receives a dead time set value T_dead and a carrier cycle Tc that are set according to variations in device breakdown voltage, temperature characteristics, and the like, and changes the dead time set value T_dead from a time unit [μs] to a duty unit [μs]. Convert to-].

The converted duty is referred to as “dead time equivalent duty”, the dead time equivalent duty during power running is represented as “duty_dead_α”, and the dead time equivalent duty during regeneration is represented as “duty_dead_β”. Further, “duty_dead_α” and “duty_dead_β” are omitted as appropriate, and expressed as “α” and “β”.
The duty “α” corresponding to the dead time during power running is input to the switching unit 64 as it is. On the other hand, the dead time equivalent duty “β” at the time of regeneration is input to the switching unit 64 as “−β” whose sign is inverted by the inverting unit 62.

  The power running / regeneration determination unit 63 determines whether it is currently in power running or regeneration based on the sign of the current IB, that is, the direction (see FIGS. 3 and 5) or the power used. The switching unit 64 switches the dead time equivalent duty output to the abnormality determination unit 65 to “α” or “−β” based on the determination result of the power running / regeneration determination unit 63. The abnormality determination unit 65 stores “α” and “−β”. The determination result of the power running / regeneration determination unit 63 is also notified to the abnormality determination unit 65.

  The abnormality determination unit 65 subtracts “−β” from “α” input from the switching unit 64 to calculate a difference value “α + β” between “α” and “−β”. Hereinafter, the difference value between “α” and “−β” is simply referred to as the sum “α + β” of the dead time equivalent duty. The abnormality determination unit 65 adds the difference value (Δ integral term) between “integral term_powering” and “integral term_regeneration” acquired from the feedback calculation unit 52 of the boost control unit 55 and the sum “α + β of the dead time equivalent duty” To determine whether the voltage converter 20 is normal or abnormal. Details of this determination method will be described later.

Next, switching operations of the switching elements 23 and 24 at the time of power running and regeneration of the voltage converter 20 will be described with reference to FIGS. In the following description, the high potential side switching element 23 is also referred to as “upper arm 23” and the low potential side switching element 24 is also referred to as “lower arm 24”.
3 and 5 show the current flowing through the voltage converter during power running and regeneration. Note that the subscript “B” of the symbol “IB” of the battery current is represented by a subscript in the drawing, and is represented by a normal character in the text of the specification.

4 and 6 are diagrams for explaining a PWM signal generated by comparing the boost carrier and the command duty. Each pulse signal indicates that the top is on and the bottom is off.
4 and 6, the “basic carrier Co” corresponding to the command duty is indicated by a solid line, and the “dead time carrier Cd” for generating a dead time is indicated by a broken line.
The dead time carrier is applied to the on timing of the upper and lower arms 23 and 24. The upper arm 23 is turned off when the duty falls below the basic carrier Co, and turns on when the duty exceeds the dead time carrier Cd. The lower arm 24 turns on when the duty falls below the dead time carrier Cd, and turns off when the duty exceeds the basic carrier Co.

4 and 6, “ideal duty not considering dead time” (original signal) calculated by the duty calculation unit 54 of the boost control unit 55 and the result of generating the dead time in the ideal duty are obtained. The relationship with the actual duty is shown.
The generation of the dead time is a period in which the upper and lower arms 23 and 24 are simultaneously turned off between the time when the upper arm 23 is turned off and the lower arm 24 is turned on and between the time when the lower arm 24 is turned off and the upper arm 23 is turned on It means to provide.
For example, assuming that the ideal duty is 0.5 (= 50%), by generating a dead time in the ideal duty, the actual duty becomes larger than 0.5 at the time of power running (FIG. 4), and at the time of regeneration (see FIG. In 6), the actual duty is smaller than 0.5.

The lower part of FIGS. 4 and 6 shows the relationship between the command duty after feedback (FB) correction and the actual duty. In this feedback correction, the actual duty obtained as a result of generating the dead time is corrected so as to coincide with the ideal duty. Therefore, a value obtained by offsetting the duty equivalent to the dead time with respect to the ideal duty is set as the command duty.
At the time of power running (FIG. 4), since the actual duty becomes larger than the ideal duty (0.5), a value obtained by subtracting the dead time equivalent duty “α” from 0.5 is set as the command duty. The actual duty after time generation is set to 0.5.
At the time of regeneration (FIG. 6), since the actual duty becomes smaller than the ideal duty (0.5), the value obtained by adding the dead time equivalent duty “β” to 0.5 is set as the command duty. The actual duty after time generation is set to 0.5.

First, FIG. 3 and FIG. 4 will be referred to in detail for powering.
In the power running shown in FIG. 3, the current IB (> 0) flows from the battery 1 side to the inverter 7 side. As indicated by the solid line, the current from the middle point N of the upper and lower arms to the high potential line Lp flows through the freewheeling diode 25 not only when the upper arm 23 is on but also when the upper arm 23 is off. On the other hand, as indicated by the broken line, the current from the intermediate point N to the low potential line Lg flows only when the lower arm 24 is on. Therefore, when a failure occurs in which the lower arm 24 is fixed off, an abnormality occurs in the power running operation. On the other hand, even if the upper arm 23 is fixed off, there is no significant influence on the power running operation except for the loss due to the resistance of the reflux diode 25 and the like. Further, as shown in FIG. 4, the actual duty corresponds to the off period of the lower arm 24.

  In FIG. 4, t2, t4, t7, and t9 are defined as timings at which the ideal duty intersects the basic carrier Co and the dead time carrier Cd in one cycle of the boost carrier. Further, t1, t3, t8, and t10 are further added as timings when the command duty after feedback correction at the time of power running intersects the carriers Co and Cd.

  For the original signal, the ideal duty on-period is t7 to t2, the upper arm 23 on-period is t9 to t2, and the lower arm 24 off-period is t7 to t4. Therefore, as indicated by a thick line (DT) in the actual duty, a period from t7 when the lower arm 24 is turned off to t9 when the upper arm 23 is turned on, and from t2 when the upper arm 23 is turned off to t4 when the lower arm 24 is turned on. This period is generated as dead time. As a result, the actual duty corresponding to the off period of the lower arm 24 becomes larger than 0.5.

  When this actual duty is fed back, the boost control unit 55 corrects so that “the value obtained by subtracting the dead time equivalent duty α from the ideal duty (0.5−α)” becomes the command duty. Then, the ON period of the command duty after feedback correction is t8 to t1, the ON period of the upper arm 23 is t10 to t1, and the OFF period of the lower arm 24 is t8 to t3. Thereby, the period from t8 to t10 and the period from t1 to t3 are generated as dead time. The actual duty corresponding to the off period of the lower arm 24 is equal to 0.5.

Next, FIG. 5 and FIG. 6 are referred about at the time of regeneration.
At the time of regeneration shown in FIG. 5, the current IB (<0) flows from the inverter 7 side to the battery 1 side. As indicated by the broken line, the current from the low potential line Lg to the middle point N of the upper and lower arms flows through the freewheeling diode 26 not only when the lower arm 24 is turned on but also when the lower arm 24 is turned off. On the other hand, as indicated by the solid line, the current from the high potential line Lp to the intermediate point N flows only when the upper arm 23 is on. Therefore, when a failure occurs in which the upper arm 23 is stuck off, an abnormality occurs in the regenerative operation. On the other hand, even if the lower arm 24 is fixed off, there is no significant influence on the regenerative operation except for loss due to the resistance of the freewheeling diode 26. Further, as shown in FIG. 6, the actual duty corresponds to the on period of the upper arm 23.

  In FIG. 6, t2, t4, t7, and t9 of FIG. 4 are used as the timing at which the ideal duty intersects the basic carrier Co and the dead time carrier Cd in one cycle of the boost carrier. Further, t3, t5, t6, and t8 are further added as timings at which the command duty after feedback correction at the time of regeneration intersects the carriers Co and Cd.

  When the original signal is expressed in reverse to the power running, the ideal duty off period is t2 to t7, the off period of the upper arm 23 is t2 to t9, and the off period of the lower arm 24 is t4 to t7. In addition, as indicated by a thick line (DT) in the actual duty, a period from t2 when the upper arm 23 is turned off to t4 when the lower arm 24 is turned on, and from t7 when the lower arm 24 is turned off to t9 when the upper arm 23 is turned on. This period is generated as dead time. As a result, the actual duty corresponding to the ON period of the upper arm 23 is smaller than 0.5.

  When this actual duty is fed back, the boost control unit 55 corrects “the value obtained by adding the dead time equivalent duty β to the ideal duty (0.5 + β)” as the command duty. Then, the off period of the command duty after feedback correction is t3 to t6, the off period of the upper arm 23 is t3 to t8, and the on period of the lower arm 24 is t5 to t6. Thereby, the period from t3 to t5 and the period from t6 to t8 are generated as dead time. Further, the actual duty corresponding to the ON period of the upper arm 23 is equal to 0.5.

As described above, when the voltage converter 20 is normally driven, the dead time equivalent duty “α” and “β” are subtracted or added to the ideal duty during power running and regeneration, respectively, while ensuring an appropriate dead time. The pressure control is performed by operating the upper and lower arms 23 and 24.
However, if an abnormality occurs in the upper arm 23 or the lower arm 24, or the return diodes 25 and 26, the voltage sensors 31 and 32, etc., the deviation between the actual duty and the command duty is equivalent to the assumed dead time equivalent duty “α ”And“ β ”.

Next, the “abnormal region” indicating the abnormality of the voltage converter 20 will be described with reference to FIGS.
The horizontal axis in FIG. 7 represents current, and when positive, indicates powering, and when negative, indicates regeneration. The vertical axis in FIG. 7 is an integral term duty_I (hereinafter, “duty_I” will be omitted as appropriate) calculated in a predetermined integration period. The duty calculation unit 54 (see FIG. 2) feeds the feedforward term duty_ff. The direction subtracted from is defined as positive.
During powering, the region where the integral term_powering value (> 0) is 0 to α is normal, and the region where the integral term_powering value is greater than α is abnormal. During regeneration, the region where the integral term_regeneration value (<0) is from 0 to (−β) is normal, and the region where the integral term_regeneration value is smaller than (−β) is abnormal.

FIG. 8 is a diagram showing the contents of FIG. 7 with duty as a parameter. The horizontal axis (x-axis) in FIG. 8 represents the feedforward term duty_ff, and the vertical axis (y-axis) represents the duty obtained by subtracting the integral term duty_I from the feedforward term duty_ff. That is, the downward direction in FIG. 8 is represented as the positive direction of the integral term duty_I. The proportional term duty_P (see FIG. 2) of the feedback term is ignored.
The feedforward term duty_ff is considered to correspond to a “command duty” determined by the output voltage command value Vsys ^* and the input voltage Vin. On the other hand, the duty obtained by subtracting the integral term duty_I from the feedforward term duty_ff is considered to correspond to the “real duty” in which the actual behavior of the voltage converter 20 is reflected in the integral term duty_I. The reference line S is a line indicating when “integration term duty_I = 0”.

When the map of FIG. 8 is actually created, a scatter diagram is created from actually measured values of dead times equivalent duty “α” and “β” in a finite number of command duties, and a primary order defined as follows: An approximate expression of the function may be obtained.
During power running: y = kpx−α0 (kp: inclination, −α0: intercept)
During regeneration: y = krx + β0 (kr: slope, β0: intercept)

During power running, since the positive integral term_power running is subtracted from the feedforward term duty_ff, the duty shifts below the reference line S (duty <duty_ff). If the value of the positive integral term_powering to be subtracted is α or less, it is normal, and if it exceeds α, it is abnormal.
At the time of regeneration, since the negative integral term_regeneration is subtracted from the feedforward term duty_ff, the duty is shifted upward from the reference line S (duty> duty_ff). It is normal if the absolute value of the negative integral term_regeneration to be subtracted is less than or equal to β, and abnormal if it exceeds β.

Therefore, if feedback control is executed based on the exact value of the output voltage Vsys, the value of the integral term is compared with the boundary line (threshold value) in FIG. 8 to evaluate whether it is in the normal region or the abnormal region. By doing so, it is considered that the abnormality of the voltage converter 20 can be detected.
By the way, regarding the abnormality detection of the voltage converter 20, for example, in the prior art of Patent Document 1, the failure of the voltage sensor is detected based on the difference voltage calculated from the detected values of the input voltage sensor and the output voltage sensor and the duty of the voltage converter. Detected. In this conventional technique, when an error or variation between two voltage sensors is taken into account, it may be difficult to set an abnormality determination value. As a result, there is a possibility that erroneous detection or detection omission may occur.

Thus, if there is an error or variation in the voltage sensor, the influence is absorbed by the integral term by feedback control. For example, assuming an offset error of the voltage sensor, the normal / abnormal boundary line in FIG. 8 is translated as indicated by a block arrow.
Then, the point Qp at the time of power running is erroneously determined to be in the abnormal region although it is originally in the normal region. On the other hand, the point Qr at the time of regeneration is erroneously determined to be in the normal region even though it is originally in the abnormal region. Therefore, if an abnormality is to be detected based on the value of one of the integral terms during power running or regeneration, erroneous detection or omission of detection may occur depending on the error or variation of the voltage sensor 32.

  Therefore, the abnormality detection unit 60 according to the present invention is characterized in that an abnormality is detected based on “a difference value (integral term) between integral terms during power running and regeneration”. Since the integral term other than the dead time is common for power running and regeneration, calculating the differential value of the integral term during power running and regeneration cancels the influence of errors and variations in the voltage sensor 32. It is. Therefore, by comparing the difference value of the integral term during power running and regeneration with the sum “α + β” of the dead time equivalent duty, the abnormality of the voltage converter 20 is not affected by the error or variation of the voltage sensor 32. Can be detected. Therefore, it is possible to prevent erroneous detection and detection omission in abnormality detection.

Next, specific examples of the abnormality detection process of the present invention will be described separately for the first embodiment and the second embodiment.
(First embodiment)
The abnormality detection process of the first embodiment will be described with reference to the flowchart of FIG. In the description of the flowchart below, the symbol “S” means a step. This routine is executed, for example, every control cycle.

In S11, based on the information from the power running / regeneration determination unit 63 (see FIG. 2), it is determined whether the current time is power running or regeneration.
“Integral term_power running (> 0)” is stored during power running (S11: YES) (S12), and “integral term_regeneration (<0)” is stored during regeneration (S11: NO) (S13). ).
In S14, a difference value “Δ integral term (= integral term_power running−integral term_regeneration)” between the integral term during power running and the integral term during regeneration is calculated.

In S15, the integral term difference value (Δ integral term) is compared with the sum “α + β” of the dead time equivalent duty during power running and regeneration. If the integral term difference value (Δ integral term) is larger than “α + β” (S15: YES), it is determined that any component of the voltage converter 20 is abnormal (S16), and the integral term difference value (Δ integral term) is “ If “α + β” or less (S15: NO), it is determined that the voltage converter 20 is normal (S17).
Depending on the definition of the signs of dead time equivalent duty α and β, it is effective to define the threshold value to be compared with the integral term difference value as “the sum of absolute values of dead time equivalent duty”.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the flowchart of FIG.
When an abnormality of the voltage converter 20 is detected in the flowchart of FIG. 9 of the first embodiment (S16), it can be seen that any part has failed, but it is not known which part has failed. Therefore, in the second embodiment, processing for further specifying an abnormal part is performed.
The idea is “Comparison of the value of the integral term at power running and the duty equivalent to dead time at power running” and “Comparison of the value of the integral term at power regeneration and dead time equivalent duty at regeneration” And determine based on the result.

S21 is a step following S16 of FIG. In S21, if the integral term_power running is greater than the dead time equivalent duty “α” during power running and the integral term_regeneration is smaller than the inverted value “−β” of the dead time equivalent duty during regeneration (S21: YES). Both power running and regeneration are determined to be abnormal (S24).
If NO in S21, in S22, if the integral term_power running is larger than α and the integral term_regeneration is equal to or greater than (−β) (S22: YES), it is determined that the power running is abnormal (S25). When the power running is abnormal, for example, there is a possibility that the lower arm 24 is off-fixed (disconnected).
If NO in S22, in S23, if the integral term_powering is less than or equal to α and the integral term_regeneration is smaller than (−β) (S23: YES), it is determined that regeneration is abnormal (S26). When the regeneration is abnormal, for example, the possibility of an off-sticking (disconnection) failure of the upper arm 23 is suspected.

  If the determination that “any part is abnormal” in S16 is correct, S21 to S23 are surely determined to be any of S24 to S26. However, if the determination in S16 is incorrect, it is determined NO in S23, and the voltage converter 20 is corrected to a normal determination (S27).

  As described above, in the second embodiment, it is possible to roughly classify whether a failed part is a part used for powering, a part used for regeneration, or a part used for both powering and regeneration. . And especially when applied to hybrid vehicles, from the viewpoint of fail-safe, use only parts that operate normally, perform only regenerative operation when power running is abnormal, and perform only power running operation when regenerative abnormality occurs Thus, it is possible to realize evacuation travel at the time of abnormality. Moreover, since it is only necessary to replace only the relevant parts when repairing the voltage converter 20, the repair cost can be reduced as compared with the case where all the parts are replaced.

  As a modification of the second embodiment, when it is desired to know only “at least power running is abnormal”, “comparison between the value of the integral term during power running and the dead time equivalent duty during power running” May only be performed. On the other hand, when only “whether at least regeneration is abnormal” is desired to be known, only “comparison between the value of the integral term during regeneration and the dead time equivalent duty during regeneration” may be executed.

(Other embodiments)
(A) The “voltage converter” to which the control device of the present invention is applied is not limited to the step-up converter that steps up the input voltage, but may be a step-down converter that steps down the input voltage. Correspondingly, the “voltage control unit” and the “voltage conversion unit” may be a step-down control unit and a step-down unit instead of the step-up control unit 55 and the step-up unit 22.

  (A) In the above embodiment, the inverter 7 that drives the motor generator 8 by converting a DC voltage into a three-phase AC voltage is illustrated as the load circuit of the voltage converter 20. In addition, as a load circuit of the voltage converter 20, for example, an H bridge circuit that drives a DC motor may be used. A plurality of load circuits may be connected to one voltage converter 20.

(C) The driving target to which power is supplied from a load circuit such as an inverter is not limited to a motor generator used as a power source of a hybrid vehicle or an electric vehicle, but is used for auxiliary equipment of vehicles, trains other than vehicles, elevators, etc. It may be a rotating machine used in a machine or the like. Also, a device using a high voltage such as a discharge tube or an X-ray generator may be used.
As mentioned above, this invention is not limited to the said embodiment at all, In the range which does not deviate from the meaning of invention, it can implement with a various form.

1 ... battery,
20 ... Voltage converter,
21: Reactor,
22 ... Booster (voltage converter),
23 ... high potential side switching element (upper arm),
24 ... low potential side switching element (lower arm),
50 ... Voltage converter control device,
55 ... Boost control unit (voltage control unit),
60: Anomaly detection unit,
7: Inverter (load circuit).

Claims (3)

A reactor (21) provided between the battery (1) and the load circuit (7) and capable of storing and releasing electric energy, and a high and repeating electric energy storage and discharging in the reactor by alternately turning on and off. A voltage converter (22) including a potential side switching element (23) and a low potential side switching element (24) is provided, and the battery side input voltage (Vin) and the load circuit side output voltage (Vsys) are powered. A voltage converter control device (50) applied to a voltage converter (20) for converting into a direction and a regeneration direction,
A feed-forward term calculated based on a ratio between an output voltage command value (Vsys ^* ) that is a target value for the output voltage and the input voltage with respect to a duty that is an on-time ratio with respect to a switching cycle of the high potential side switching element. And a voltage control unit (55) for adding and subtracting a feedback term including a proportional term and an integral term calculated so as to make the detected value of the output voltage coincide with the output voltage command value, and outputting the result to the voltage converting unit. ,
The difference value of the integral term calculated during a predetermined integration period during power running and regeneration, and the dead time equivalent duty calculated based on the dead time setting value and carrier cycle of the voltage conversion unit during power running and regeneration An abnormality detection unit (60) for detecting an abnormality of the voltage converter by comparing the sum of absolute values of
A voltage converter control device comprising: The abnormality detection unit
When an abnormality of the voltage converter is detected, a comparison between the value of the integral term during power running and the duty equivalent to the dead time during power running, or the value of the integral term during regeneration and the dead time during regeneration The voltage converter control device according to claim 1, wherein at least one of the comparison with the equivalent duty is executed. The abnormality detection unit
When an abnormality of the voltage converter is detected, the value of the integral term during power running is compared with the duty equivalent to the dead time during power running, and the value of the integral term during regeneration and the dead time during regeneration 3. The voltage converter control device according to claim 2, wherein any comparison with the equivalent duty is executed.

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