JP2011015597A - Power conversion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion apparatus capable of reducing cost with a configuration smaller than the conventional one.SOLUTION: The power conversion apparatus 20 has a power conversion unit 21 for converting a power supplied from a power supply and for output of the converted power, and a controller 22 for performing drive control of switching elements Q1-Q6 (switching element group) which constitute the power conversion unit 21. The switching elements Q1-Q6 include sense terminals S1-S6 for outputting sense currents. Resistors R1-R6 are connected to the sense terminals S1-S6. The controller 22 is built in the power conversion unit 21, and has a recording medium for recording the correlation between the sense current and a sense voltage applied to both ends of the resistors R1-R6, and device control means for controlling the operation state of a generator motor 30 (output device) based on the sense current obtained from the detected sense voltage according to the correlation. By this configuration, a protection circuit and a current sensor that are conventionally necessary, become unnecessary.

Description

  The present invention relates to a power conversion device having a power conversion unit and a control unit.

  Conventionally, an example of an abnormality detection device that detects an abnormality when a current flowing through an electric motor is detected by a current sensor and a current exceeding an allowable value occurs at a predetermined frequency or more is disclosed (for example, see Patent Document 1). . According to this technology, a control unit (for example, a microcomputer, a controller, etc.) is not abnormal when the current temporarily exceeds the allowable value due to noise or the like, and abnormal when the current continuously exceeds the allowable value. Is determined. In addition, although there is no specific description in Patent Document 1, it is necessary to provide a protection circuit for protecting the switching element because the current exceeds the allowable value although it is temporary.

  As a method for reducing the cost, an example of an overcurrent detection circuit configured using an analog circuit to prevent a delay in overcurrent detection due to AD conversion using a switching element having a sense terminal is disclosed (for example, Patent Documents). 2). According to this technique, in order to be able to shut off the switching element at a high speed when an overcurrent is detected, it is determined whether the current flowing through the sense terminal exceeds an allowable value. However, since the current flowing through the sense terminal has a characteristic depending on temperature, the current value is compensated by the temperature.

Japanese Patent Laid-Open No. 10-309097 JP 2008-136335 A

  However, in any of the techniques disclosed in Patent Documents 1 and 2, it is necessary to provide a protection circuit for protecting the switching element. In the technique of Patent Document 1, a current sensor must be provided separately. Therefore, there is a problem that the configuration becomes large and the cost increases.

  This invention is made | formed in view of such a point, and it aims at providing the power converter device which can make a structure smaller than before and can reduce cost.

The invention according to claim 1, which has been made to solve the above problems, drives a power conversion unit that converts power supplied from a power source and outputs the power to an output device, and a switching element group that constitutes the power conversion unit. In the power conversion device having a control unit to control, each switching element of the switching element group includes a sense terminal that outputs a sense current, a resistor is connected to the sense terminal,
The control unit is incorporated in the power conversion unit, and obtains a recording medium for recording a correlation between the sense current and a sense voltage applied to both ends of the resistor, and a detected detection voltage according to the correlation. Device control means for controlling an operating state of the output device based on the sense current.

  Note that “power source” includes a converter and the like in addition to the power source itself. As the “output device”, any device that can operate by receiving the power output from the power conversion unit can be applied. For example, one or more of a rotating machine (that is, a generator, a motor, a generator motor, etc.), a power system, a load, and the like are applicable. As the “switching element (group)”, any semiconductor element having a switching function can be used, for example, an IGBT or a power transistor.

  According to this configuration, since the control unit is built in the power conversion unit, the sense voltage applied to both ends of the resistor connected to the sense terminal is directly input to the control unit. The overcurrent control means provided in the control unit first obtains a sense current corresponding to the input sense voltage. Specifically, it is determined based on the correlation information recorded on the recording medium. Correlation information may be arbitrarily defined. For example, there are a method expressed in a data table format, a method expressed in a function format, and the like. Based on the sense current thus obtained, the device control means controls the operating state of the output device. The control of the operating state varies depending on the output device. For example, in the case of a rotating machine, control of torque, rotation speed, and the like is applicable. Therefore, since the protection circuit and the current sensor that are necessary in the conventional technique are not necessary, the configuration can be made smaller than the conventional one, and the cost can be reduced. Note that any element can be used as the switching element as long as it has a sense terminal. For example, a semiconductor element such as an IGBT or a power MOSFET is applicable.

  The invention according to claim 2 is characterized in that, when the output device is a rotating machine, the device control means controls one or both of the torque and the rotational speed of the output device according to the sense current. To do. According to this configuration, since a current sensor is not necessary, the cost can be reduced.

  According to a third aspect of the present invention, there is provided overcurrent control means for performing control for protecting the switching element group when the sense voltage to be detected becomes the sense current outside a predetermined range. According to this configuration, when the sense current is outside the predetermined range, the overcurrent control unit performs control for protecting the switching element group. For example, the control for stopping the driving of the switching element group and the control for reducing the driving of the switching element group are applicable. Therefore, since a protection circuit and a current sensor are not necessary, the configuration can be made smaller than before, and the cost can be reduced.

  The invention according to claim 4 is characterized in that the overcurrent control means performs control to stop driving of the switching element group or control to reduce driving of the switching element group. According to this configuration, the overcurrent control unit performs control for stopping the driving of the switching element group or performs control for reducing the driving of the switching element group. In any control, it is possible to reliably prevent an overcurrent from flowing through the switching element.

  According to a fifth aspect of the present invention, when the sense current exceeds a normal limit value, the overcurrent control unit performs control to reduce driving of the switching element group, and further, when the sense current exceeds an allowable value, Control for stopping driving of the switching element group is performed. According to this configuration, stepwise depending on whether the sense current exceeds the normal limit value (that is, the limit value of the current that flows by normal drive control) or further exceeds the allowable value (that is, the upper limit value that can be passed to the switching element). The switching element group is controlled. By controlling in stages, it is possible to reliably prevent an overcurrent from flowing through the switching element.

  The invention according to claim 6 records the correlation between the sense current and the sense voltage on the recording medium corresponding to one or both of the gate voltage and the temperature applied to the target switching element. It is characterized by that. According to this configuration, the correlation between the sense current and the sense voltage is recorded for each voltage for a plurality of gate voltages, or is recorded for each temperature for a plurality of temperatures. A correlation corresponding to one or both of the gate voltage and the temperature may be recorded in accordance with the characteristics of each switching element constituting the power conversion unit. By doing so, it becomes possible to deal with the dependency of the switching element, and the sense current corresponding to the use environment can be obtained more accurately. Therefore, it is possible to accurately protect the switching element group in any use environment.

  The invention according to claim 7 is characterized in that the control unit inputs one or both of the gate voltage and the temperature, and specifies the sense current based on the input information. According to this configuration, one or both of the gate voltage and the temperature are directly input to the control unit. The temperature depends on the signal content output from the detector, and is a voltage correlated with the temperature (for example, 1.5 [V] at 25 [° C]) or the data of the temperature itself (for example, 25 [° C]). Sometimes digital data representing 25). Since the sense current according to the usage environment can be obtained more accurately, the switching element group can be protected accurately.

  The invention according to claim 8 is characterized in that information on a characteristic line indicating a correlation between the sense current and the sense voltage is recorded on the recording medium. According to this configuration, the correlation between the sense current and the sense voltage is represented by the characteristic line, and information about the characteristic line is recorded on the recording medium. Since the characteristic line can be expressed by a straight line or a curve, the information on the characteristic line is information for specifying the function. The data table increases the amount of information, but the function can reduce the amount of information required. Therefore, the recording capacity required for the recording medium can be reduced, and the cost can be reduced.

  The invention according to claim 9 is characterized by comprising a notifying means for notifying an external device of information relating to the control performed by the device control means and the overcurrent control means. According to this configuration, the notification unit notifies the external device of information related to control. Information relating to control can be arbitrarily set, and for example, one or more pieces of information such as a sense current, a sense voltage, a gate voltage, and a temperature are applicable. If it carries out like this, an external device can grasp | ascertain the state of a power converter device, and can perform the command with respect to a power converter device next.

It is a schematic diagram which shows the structural example of a power converter device. It is a circuit diagram which shows the example of a connection centering on a switching element. It is a schematic diagram which shows the structural example of a controller. It is a graph which shows an example of correlation with a sense current and a sense voltage. It is a graph which shows the correlation for every gate voltage and temperature. It is a flowchart which shows the example of a procedure of a sense current control process. It is a time chart which shows the change of the sense voltage with respect to a phase current. It is a graph explaining a measure when an overcurrent occurs. It is a graph explaining a measure when an overcurrent occurs.

  Below, the form for implementing this invention is demonstrated based on drawing. Unless otherwise specified, “connect” means electrical connection. Further, the continuous code is expressed using the symbol “˜”. For example, “switching elements Q1 to Q6” means “switching elements Q1, Q2, Q3, Q4, Q5, Q6”. As an output device, an example in which a vehicular generator motor capable of both engine starting and power generation is applied will be described.

  First, in FIG. 1, the structural example of a power converter device is shown with a schematic diagram. The power conversion device 20 shown in FIG. 1 has a function of converting the power supplied via the converter circuit 10 and outputting it to the generator motor 30. The power conversion device 20 includes a power conversion unit 21, a controller 22, insulation units 23 and 24, and the like. A smoothing capacitor C <b> 2 is connected between the converter circuit 10 and the power conversion device 20. The capacitor C2 reduces potential fluctuations in the DC power supply voltage input from the converter circuit 10.

  The converter circuit 10 uses a DC voltage V10 (for example, 12 volts or the like) supplied from a first power source E1 (for example, a battery) via a smoothing capacitor C1 for a DC voltage V10 (for example, a voltage required by the power converter 20). 650 volts or the like) and output. Since the configuration and operation of the converter circuit 10 are well known, illustration and description thereof are omitted.

  The power conversion device 20 includes a power feeding function and a power transmission function that can be switched. The power feeding function is a function of converting DC power supplied from the first power supply E1 via the converter circuit 10 into three-phase AC power and supplying the three-phase AC power to the generator motor 30. The power transmission function is a function of rectifying the three-phase AC power generated by the generator motor 30 and returning it to the first power supply E1 via the converter circuit 10.

  The power conversion unit 21 includes drive circuits M1 to M6, switching elements Q1 to Q6, diodes D1 to D6, resistors R1 to R6, and the like. The temperature-sensitive diodes Dθ1 to Dθ6 whose illustration is omitted will be described later (see FIG. 2). Drive circuits M1 to M3, switching elements Q1 to Q3, diodes D1 to D3, resistors R1 to R3, and the like are arranged on the upper arm side. Drive circuits M4 to M6, switching elements Q4 to Q6, diodes D4 to D6, resistors R4 to R6, and the like are arranged on the lower arm side.

  The drive circuits M <b> 1 to M <b> 6 operate by receiving a voltage supply from the control power supply 50. The drive circuits M1 to M6 may operate by receiving supply from a power source controlled (for example, a step-down power source) from the first power source E1. The drive circuits M1 to M6 drive signals to control terminals (for example, gate terminals) of the corresponding switching elements Q1 to Q6 in accordance with control signals (for example, PWM (pulse width modulation) signals and the like) individually transmitted from the controller 22. Is output. The reference potential differs between the voltage received by the drive circuits M1 to M3 via the control terminals Pi1 to Pi3 and the voltage received by the drive circuits M4 to M6 via the control terminals Pi4 to Pi6. This is because a gate voltage is formed with reference to a predetermined terminal (for example, an emitter terminal) of a semiconductor switching element (for example, an IGBT). Since the reference potentials also differ between the control terminals Pi1 to Pi3 and the sense terminals Ps1 to Ps3 of the switching elements Q1 to Q3 described later, an insulating element (or high withstand voltage element) is required to ensure insulation.

  As the switching elements Q1 to Q6 corresponding to the “switching element group”, for example, an IGBT including sense terminals S1 to S6 for outputting a sense current is used. Resistors R4 to R6 are connected between the sense terminals Ps4 to Ps6 and the common potential G2, respectively. Resistors R1-R3 are connected to the emitter terminals of corresponding switching elements Q1-Q3, respectively. The common potential G2 is a common potential (same potential ground) in the power conversion device 20, and when the power conversion device 20 is connected to the ground G1, it has the same potential as the ground. Since the common potential G2 is generally not the same potential as the ground, the common potential G2 is illustrated using a different symbol from the ground G1. Here, in FIG. 1, some elements are omitted for simplicity of illustration, and a specific connection example of the switching elements Q <b> 1 to Q <b> 6 will be described with reference to FIG. 2.

  FIG. 2 shows a connection example centered on the switching element Qn. When any numerical value of 1 to 6 is applied to n, it corresponds to any one of the switching elements Q1 to Q6 shown in FIG. The same applies to the following description. In other words, the switching element Qn is a circuit element described as a representative of the switching elements Q1 to Q6, and the other circuit elements shown are the same. However, the switching elements Q1 to Q3 of the upper arm are not connected to the common potential G2 (see FIG. 1).

  The circuit element not shown in FIG. 1 is a temperature sensitive diode Dθn that detects the temperature of the switching element Qn. The temperature-sensitive diode Dθn has an anode connected to the control power supply 50 and a cathode connected to the common potential G2. A constant current is supplied from the control power supply 50 to the temperature sensitive diode Dθn, and the voltage applied to both ends of the temperature sensitive diode Dθn correlates with the temperature θn. As an example, if the voltage applied to the temperature sensitive diode Dθn is 2 [V], it indicates that the temperature of the switching element Qn is 20 [° C.].

  The sense voltage Vsen across the resistor Rn has a correlation with the sense current Isn flowing through the sense terminal Sn. This correlation will be described later (see FIGS. 4 and 5). The above-described sense voltage Vsen, temperature θn, gate voltage Vgn applied to the gate terminal of the switching element Qn, inter-terminal voltage Vcen generated between the collector terminal and the emitter terminal of the switching element Qn, etc. are input to the controller 22. (See FIG. 3).

  Returning to FIG. 1, the diodes D1 to D6 are connected in parallel between the collector terminals and the emitter terminals of the corresponding switching elements Q1 to Q6, respectively. These diodes D1 to D6 all function as freewheeling diodes.

  The circuit elements in the power converter 21 are divided into three phases (U phase, V phase, and W phase in this example) as shown surrounded by a one-dot chain line, and the operation is controlled for each phase by the controller 22. The U phase includes drive circuits M1 and M4, switching elements Q1 and Q4, diodes D1 and D4, resistors R1 and R4, and the like. The V phase is composed of drive circuits M2 and M5, switching elements Q2 and Q5, diodes D2 and D5, resistors R2 and R5, and the like. The W phase is composed of drive circuits M3 and M6, switching elements Q3 and Q6, diodes D3 and D6, resistors R3 and R6, and the like. The U-phase switching elements Q1 and Q4 are connected in series to form a half bridge. Similarly, the V-phase switching elements Q2 and Q5 and the W-phase switching elements Q3 and Q6 are connected in series to form a half bridge. Each connection point of the half bridge and the three-phase terminal of the generator motor 30 are connected for each phase by lines Ku, Kv, Kw. A U-phase current Iu flows through the line Ku, a V-phase current Iv flows through the line Kv, and a W-phase current Iu flows through the line Kw (see FIG. 7).

  The controller 22 corresponding to the “control unit” is built in the power conversion device 20 and controls the operation of the converter circuit 10, the power conversion device 20, and the like. For example, a control signal (for example, a PWM signal) for controlling the converter circuit 10, the power converter 20, or the like is output based on signal information input via the insulating units 23 and 24. The input signal information includes, for example, a command signal (for example, a torque command, a rotation speed command, etc.) transmitted from an external ECU (that is, an external control device), a rotation angle sensor 40 provided on the generator motor 30 side, and the like. This applies to detection signals. Further, signal information is output to the external ECU through the insulating unit 23, and signals (for example, excitation signals and detection signals) are input to and output from the rotation angle sensor 40 through the insulating unit 24 and the signal converting unit 25. .

  A description will be given with reference to FIG. The controller 22 shown in FIG. 3 includes a recording medium 22a, device control means 22b, overcurrent control means 22c, notification means 22d, and the like. The recording medium 22a records the correlation between the sense current Isn and the sense voltage Vsen shown in FIG. Specific information to be recorded will be described later (see FIGS. 4 and 5). As long as this correlation can be recorded, any medium may be used as the recording medium 22a. For example, ROM, EEPROM, magneto-optical disk, and the like are applicable.

  The device control means 22b controls the operating state (for example, the rotational speed) of the generator motor 30 based on the sense currents Is1 to Is6. The overcurrent control unit 22c performs control for protecting the switching elements Q1 to Q6 when detecting the sense currents Is1 to Is6 in which the sense voltages Vse1 to Vse6 are outside the predetermined range. The notification unit 22d notifies the external ECU of information related to protection when performing control to protect the switching elements Q1 to Q6.

  As long as the functions described above are performed, the controller 22 may be arbitrarily configured. For example, a software control may be performed by a CPU (including a microcomputer), or a hardware control may be performed using an electronic component such as an IC (including an LSI or a gate array) or a transistor.

  Returning to FIG. 1 again, for the insulating parts 23 and 24, for example, one of a photoelectric element (for example, a photocoupler), a magnetic coupling element (for example, a transformer or a coil), a capacitive element (for example, a capacitor), or the like is provided. Use. The generator motor 30 performs both engine start and power generation. As the rotation angle sensor 40, a sensor capable of detecting the rotation angle and the rotation position of the rotor included in the generator motor 30, for example, a resolver is used.

  The control power supply 50 has a function of converting a DC voltage V2 (for example, 5 volts) supplied from the second power supply E2 into a voltage or current required by the controller 22, the drive circuits M1 to M6, and the like, and outputting the converted voltage or current. Since the configuration and operation of the control power supply 50 are well known, illustration and description thereof are omitted. As the second power source E2, for example, a battery is used in the same manner as the first power source E1. The control power supply 50 and the second power supply E2 are grounded to the ground G1.

  The correlation recorded on the recording medium 22a will be described with reference to FIGS. In the description, the reference numerals shown in FIG. 2 are used. FIG. 4 is a graph showing the correlation with the sense current Isn as the vertical axis and the sense voltage Vsen as the horizontal axis. However, since the operating characteristics of the switching element (IGBT) depend on the gate voltage Vgn, the temperature θn of the element itself, and the like, this is an example when the gate voltage Vgn is 15 [V] and the temperature θn is 150 [° C.].

  Measurement is performed in advance using a measuring device or the like before the switching elements Q1 to Q6 are incorporated in the power conversion unit 21. All switching elements are preferably measured. However, when one type of switching elements that exhibit almost the same operating characteristics with little individual difference is used, each type may be targeted. Specifically, conditions are set so that a predetermined sense current Isn flows through the switching element, and the sense voltage Vsen under the condition settings is measured with a voltmeter. Furthermore, it is desirable to measure the current flowing between the input / output terminals of the switching element (for example, between the collector terminal and the emitter terminal) with an ammeter. Although the magnitude of the sense current Isn flowing through the switching element is arbitrary, the measurement is performed at a plurality of points including the limit value (normal limit value or allowable value) of the allowable range for the switching element. As the number of measurement points increases, it becomes easier to accurately specify the operating characteristics of the switching element to be measured.

  FIG. 4 shows an example in which 11 points are measured, and each measurement point is plotted with a black circle. Based on the data thus measured, a characteristic line X representing the operating characteristics of the switching element (IGBT) is determined. In determining the characteristic line X, a mathematical method (for example, least square method or regression analysis) that can obtain an approximate line using a specific function (eg, linear function, hyperbolic function, inverse hyperbolic function, logarithmic curve, etc.) is applied. May be. In addition to one or both of the gate voltage Vgn and the temperature θn described above, information for specifying the function may be recorded on the recording medium 22a, so that the data amount can be reduced. Note that only the information of the measured data itself may be recorded on the recording medium 22a, or may be recorded together with information on a specific function. Furthermore, corresponding to the sense current Isn, the current flowing between the input and output terminals of the switching element (that is, the current flowing to the generator motor 30) and the operating state of the generator motor 30 (for example, one or both of torque and rotation speed). It is desirable to record them together.

  FIG. 4 shows an example in which the gate voltage Vgn is 15 [V] and the temperature θn is 150 [° C.], but the gate voltages Vgn are 15 [V], 14 [V], 13 [V], and the temperature θn. FIG. 5 shows an example when -40 [° C.] and 150 [° C.]. That is, FIG. 5 shows six characteristic lines X1 to X6. Characteristic lines X1 to X3 indicate changes in temperature θn of −40 [° C.], and characteristic lines X4 to X6 indicate changes in temperature θn of 150 [° C.]. One or both of the gate voltage Vgn and the temperature θn may be changed. Thus, various gate voltages Vgn and temperatures θn are measured, and one or both of information on a specific function and information of the measured data itself are recorded on the recording medium 22a. It is desirable that the number of points of the gate voltage Vgn and the temperature θn is as large as possible within the range that can be recorded on the recording medium 22a.

  In the power conversion device 20 described above, sense current control, which is one of the controls executed by the controller 22, will be described with reference to FIGS. The sense current control process shown in the flowchart of FIG. 6 is repeatedly executed when the controller 22 is operating. Note that steps ST10 to ST16 in FIG. 6 are an example in which the device control means 22b is embodied, steps ST17 to ST19 are examples in which the overcurrent control means 22c is embodied, and step ST20 is an embodiment of the notification means 22d. This is an example. FIG. 7 shows changes in the sense voltage with respect to the phase current. 8 and 9 show an example of measures when an overcurrent occurs.

  In the sense current control process shown in FIG. 6, first, a rotation angle related to rotation control performed on the generator motor 30 is acquired [step ST10], and a switching element through which a current flows is specified based on the acquired rotation angle [step S11. ]. Information such as the gate voltage Vgn, the temperature θn, and the sense voltage Vsen is input for the switching element Qn identified in step S11 from among the switching elements Q1 to Q6 [step ST12].

  The background for performing the processes of steps ST10 to ST12 is as shown in FIG. That is, as shown in FIG. 7, when the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw are flowing, the controller 22 performs control based on the pulse width modulation waveform PWM, so the switching elements Q4 to Q6 of the lower arm The sense voltages Vse4 to Vse6 can be detected only when the pulse width modulation waveform PWM is turned on. For example, as shown by the sense voltage Vse4 for the switching element Q4, the electrical angle as the rotation angle is from 30 degrees to 60 degrees, from 90 degrees to 120 degrees, from 150 degrees to 180 degrees. For the switching element Q5, as indicated by the sense voltage Vse5, the electrical angle is from 150 degrees to 180 degrees, from 210 degrees to 240 degrees, from 270 degrees to 300 degrees. As for the switching element Q6, as shown by the sense voltage Vse6 with respect to the sense voltage Vse6, the electrical angle is from 270 degrees to 300 degrees, from 330 degrees to 0 degrees, from 30 degrees to 60 degrees.

  Returning to FIG. 6, the characteristic line X recorded on the recording medium 22a is specified based on the gate voltage Vgn and the temperature θn in the information input in step ST12 [step ST13]. Further, based on the sense voltage Vsen input in step ST12 and the characteristic line X specified in step ST13, the currently flowing sense current Isn is obtained [step ST14]. For example, when the characteristic line X shown in FIG. 8 is specified in step ST13, if the sense voltage Vsen is Vx, Ix is obtained as the sense current Isn.

  Based on the sense current Isn obtained in step ST14, it is determined whether or not the operating state of the generator motor 30 (for example, one or both of the torque and the rotational speed) is different from the target value [step ST15]. The target value sets the numerical value of the operating state to be compared with the sense current Isn. When the current flowing between the input / output terminals of the switching element corresponding to the sense current Isn is recorded on the recording medium 22a, the numerical value of the operating state to be compared with the current flowing between the input / output terminals is set. Also good. If the operating state of the generator motor 30 is the same as the target value (NO), the process proceeds to step ST17 described later. “Same as target value” may determine whether the value is the same as the target value, and whether or not it is within a certain range from the target value (for example, within a range of several percent based on the target value) It may be judged.

  On the other hand, if the operating state of the generator motor 30 is different from the target value (YES), control is performed to drive the switching elements Q1 to Q6 by changing the duty ratio of the pulse width modulation waveform PWM so as to approach the target value [Step] ST16], the process proceeds to step ST17 described later. The degree to which the duty ratio should be changed varies depending on the control target (operating state), and the specific control content is well known and will not be described.

  Next, it is determined whether or not the sense current Isn obtained in step ST14 is within an allowable range [step ST17]. The allowable range is usually different between the switching elements Q1 to Q6 and the generator motor 30. Further, the target value (normal limit value or allowable value) for determining whether or not it is within the allowable range varies depending on whether one or both of steps ST18 and ST19 described later are executed. The normal limit value means a limit value of a current flowing through the switching elements Q1 to Q6 by normal drive control. The allowable value means the limit value (upper limit value) of the current that can be passed through the switching elements Q1 to Q6. When both steps ST18 and ST19 are executed, the normal limit value is applied before reaching the normal limit value, and the allowable value is applied after reaching the normal limit value.

  If the sense current Isn is within the allowable range (YES), since both the switching elements Q1 to Q6 and the generator motor 30 are operating normally, the process proceeds to step ST20 as it is. On the other hand, if the sense current Isn is outside the allowable range (NO), it is considered that an overcurrent flows through the switching element Qn specified in step S11. Therefore, one of the control for driving the switching elements Q1 to Q6 (step ST18) and the control for stopping all the driving of the switching elements Q1 to Q6 (step ST19) so that the average output voltage output to the generator motor 30 is lowered. Or both are performed and it progresses to step ST20. And the information regarding control is alert | reported to external ECU [step ST20], and a sense current control process is returned. The information to be notified can be arbitrarily set, and for example, one or more pieces of information among the information such as the sense current Isn, the sense voltage Vsen, the gate voltage Vgn, the temperature θn, and the like are applicable.

  Here, specific control contents of steps ST18 and ST19 will be described with reference to FIGS. 8 and 9 show an example in which the characteristic line X5 shown in FIG. 5 is specified in step ST13 of FIG. In FIG. 8 and FIG. 9, the measures between the normal limit value and the allowable value are different. The normal limit value corresponds to the sense current Idw and the sense voltage Vdw shown in FIG. The allowable value corresponds to the sense current Imax and the sense voltage Vmax shown in FIGS.

  First, the measure according to FIG. 8 executes one of steps ST18 and ST19. That is, when the sense current Isn obtained in step ST14 exceeds the sense current Imax and falls within the range indicated by the cross hatch, the switching elements Q1 to Q6 are driven so that the average output voltage output to the generator motor 30 decreases ( In step ST18), or all the driving of the switching elements Q1 to Q6 is stopped (step ST19). In any case, it is possible to reliably prevent an overcurrent from flowing through the switching elements Q1 to Q6.

  The measure according to FIG. 9 executes both steps ST18 and ST19. That is, when the sense current Isn obtained in step ST14 exceeds the sense current Idw and falls within the hatched hatched range, the switching elements Q1 to Q6 are driven so that the average output voltage output to the generator motor 30 is reduced (step ST18). Further, when the sense current Isn exceeds the sense current Imax and falls within the cross hatch range, the driving of the switching elements Q1 to Q6 is all stopped (step ST19). By controlling in stages in this way, it is possible to reliably prevent an overcurrent from flowing through the switching elements Q1 to Q6.

  According to the embodiment described above, the following effects can be obtained. First, corresponding to claim 1, since the controller 22 (control unit) is built in the power conversion unit 21, the sense voltage applied to both ends of the resistor Rn (R1 to R6) connected to the sense terminal Sn (S1 to S6). Vsen (Vse1 to Vse6) is directly input to the controller 22 (see FIGS. 1 and 2). The device control means 22b provided in the controller 22 obtains a sense current Isn (Is1 to Is6) corresponding to the input sense voltage Vsen (see steps ST10 to ST14 in FIG. 6). If the sense current Isn is different from the target value, the device control means 22b is configured to control the operating state of the generator motor 30 (output device) based on the sense current Isn (Is1 to Is6) (step ST15 in FIG. 6, (See ST16). According to this configuration, the current flowing between the input / output terminals of the switching element can be estimated based on the sense current Isn, and the protection circuit and the current sensor that are necessary in the prior art are not necessary. Therefore, the configuration can be made smaller than before, and the cost can be reduced.

  Corresponding to claim 2, the device control means 22b is configured to control one or both of the torque and the rotational speed of the generator motor 30 according to the sense current Isn (see steps ST15 and ST16 in FIG. 6). According to this configuration, control can be performed based on the sense current Isn, and a current sensor is not necessary, so that cost can be reduced.

  Corresponding to claim 3, when the sense current Isn falls outside the predetermined range, the overcurrent control means 22c is configured to perform control for protecting the switching elements Q1 to Q6 (see steps ST17 to ST19 in FIG. 6). . According to this configuration, it is only necessary to monitor the sense current Isn, and a protection circuit and a current sensor are not required. Therefore, the configuration can be made smaller than the conventional one, and the cost can be reduced.

  Corresponding to claim 4, the overcurrent control means 22c is configured to control to stop driving of the switching elements Q1 to Q6 or to control to reduce driving of the switching elements Q1 to Q6 (FIG. 6). (See steps ST18 and ST19 and FIGS. 8 and 9). According to this configuration, it is possible to reliably prevent an overcurrent from flowing through the switching elements Q1 to Q6 regardless of which control is performed.

  Corresponding to claim 5, the overcurrent control means 22c performs control to reduce the drive of the switching elements Q1 to Q6 when the sense current Isn exceeds the normal limit value, and further switches when the sense current Isn exceeds the allowable value. The control is performed to stop the driving of Q1 to Q6 (see steps ST18 and ST19 of FIG. 6 and FIGS. 8 and 9). According to this structure, it can prevent reliably that an overcurrent flows into switching element Q1-Q6 by controlling in steps.

  Corresponding to claim 6, the recording medium 22a is configured to record a correlation corresponding to one or both of the gate voltage and the temperature in accordance with the characteristics of each switching element constituting the power converter 21. According to this configuration, the sense current Isn corresponding to the use environment can be obtained more accurately corresponding to the dependency of the switching elements Q1 to Q6. Therefore, the switching elements Q1 to Q6 can be properly protected in any use environment.

  Corresponding to claim 7, one or both of the gate voltage Vgn and the temperature θn is directly input to the controller 22 to specify the sense current Isn (see FIGS. 1, 2, and 6). According to this configuration, since the sense current Isn corresponding to the use environment can be obtained more accurately, the switching elements Q1 to Q6 can be protected accurately.

  Corresponding to claim 8, the recording medium 22a is configured to record information on the characteristic line indicating the correlation between the sense current Isn and the sense voltage Vsen (see FIGS. 4 and 5). According to this configuration, the recording capacity required for the recording medium 22a can be suppressed to a low level, and the cost can be reduced.

  Corresponding to claim 9, the notification means 22d is configured to notify the external ECU (external device) of information relating to the control performed by the device control means 22b and the overcurrent control means 22c (see step ST20 in FIG. 6). According to this configuration, the external ECU can grasp the state of the power conversion device 20, and can then issue a command to the power conversion device 20.

[Other Embodiments]
Although the form for implementing this invention was demonstrated above, this invention is not limited to the said form at all. In other words, various forms can be implemented without departing from the scope of the present invention. For example, the following forms may be realized.

  In the embodiment described above, the IGBT is applied to the switching elements Q1 to Q6 (see FIG. 1), but other switching elements having a switching function and a sense terminal may be applied. Examples of other switching elements include power transistors such as power MOSFETs, SiC power elements, and GTO. Further, although a resolver is applied to the rotation angle sensor 40 (see FIG. 1), an arbitrary sensor (for example, an absolute rotary encoder) capable of detecting an accurate rotation angle, rotation position, etc. of a rotating body (for example, a rotor). Etc.) may be applied. Furthermore, although the temperature sensing diode Dθn is applied to the temperature sensing element that detects the temperature of the switching element Qn (see FIG. 2), other temperature sensing elements (for example, thermistor, thermocouple, etc.) that can detect the temperature of the switching element Qn. , Pin photodiodes, etc.) may be applied. In any case, since it is merely a difference in elements, the same effect as the above-described embodiment can be obtained.

  In the above-described embodiment, the generator motor 30 as the output device is applied (see FIG. 1), but other output devices that operate by receiving the power converted by the power conversion device 20 may be applied. For example, one or more of the motor, the power system, the load, and the like correspond to the other output devices. Since any output device is merely a difference between devices, the same effects as those of the above-described embodiment can be obtained.

  In the embodiment described above, the power conversion unit 21 of the power conversion device 20 is configured in three phases according to the three-phase generator motor 30 and includes six switching elements Q1 to Q6 (see FIG. 1). Instead of this configuration, the power conversion unit 21 may be configured with three phases, but may include three switching elements corresponding to one of the upper and lower arms. Further, when the output device such as the generator motor 30 has a number of phases other than three phases (for example, single phase, two phases, four or more phases), the number of switching elements corresponding to the number of phases may be provided. In any case, since only the difference in the number of switching elements constituting the switching element group is obtained, the same operational effects as those of the above-described embodiment can be obtained.

  In the above-described embodiment, the switching elements Q1 to Q6 and the diodes D1 to D6 are configured separately (see FIGS. 1 and 2), but since both are semiconductors, integrated elements may be used. . Furthermore, an element in which the temperature sensitive diodes Dθ1 to Dθ6 are integrated may be used. Similarly, in the above-described embodiment, the converter circuit 10 is configured to be provided outside the power conversion device 20 (see FIG. 1), but may be configured to be built in the power conversion device 20. Since it is merely a difference in whether the form is separate or integrated, and the function is the same, the same effect as the above-described embodiment can be obtained.

  In the embodiment described above, the characteristic line X is determined every time the gate voltage Vgn and the temperature θn are different (see FIGS. 4 and 5). Instead of this form, the characteristic line X may be determined every time only the gate voltage Vgn is different, or the characteristic line X may be determined every time only the temperature θn is different. Furthermore, except for the combination of the gate voltage Vgn and the temperature θn, two or more of the gate voltage Vgn, the temperature θn, and the inter-terminal voltage Vcen may be combined, and the characteristic line X may be determined every time the combined elements are different. . It is desirable to select an optimum standard for determining the characteristic line X according to the characteristics of the switching element. In this way, the characteristic line X suitable for the characteristics of the switching element can be determined, and it is possible to more reliably prevent an overcurrent from flowing through the switching elements Q1 to Q6.

  In the above-described embodiment, the sense current Isn is obtained from the input sense voltage Vsen based on the characteristic line X (X1 to X6) (see step ST14 in FIGS. 5 and 6). When only the measurement data (sense voltage, sense current, etc.) is recorded on the recording medium 22a, if the input sense voltage Vsen is a value other than the recorded measurement data, the nearest two of the recorded measurement data are recorded. These data may be obtained by interpolation. This also applies to the characteristic line X determined for each gate voltage Vgn and temperature θn. Although a certain amount of error occurs, since it can be controlled by the interpolated value, it is possible to obtain the same effect as the above-described embodiment.

  In the above-described embodiment, the switching elements Q1 to Q6 included in the power conversion unit 21 (see FIG. 1) and the recording medium 22a included in the controller 22 (see FIG. 3) are all configured to be non-replaceable. Instead of this form, the switching elements Q1 to Q6 and the recording medium 22a may be configured to be replaceable. In this way, it is possible to easily replace the switching element in which performance degradation or failure has occurred. Further, by switching to a recording medium 22a that records information on a characteristic line indicating the correlation between the sense current and the sense voltage for the switching element to be newly replaced, control according to the switching element after replacement can be performed.

DESCRIPTION OF SYMBOLS 10 Converter circuit 20 Power converter 21 Power converter 22 Controller (control part)
22a Recording medium 22b Device control means 22c Overcurrent control means 22d Notification means 23, 24 Insulation part 30 Generator motor 40 Rotation angle sensor 50 Control power supply E1 First power supply (power supply)
E2 Second power supply Mn (M1, M2, M3, M4, M5, M6) Drive circuit Qn (Q1, Q2, Q3, Q4, Q5, Q6) Switching element Dn (D1, D2, D3, D4, D5, D6) Diode Rn (R1, R2, R3, R4, R5, R6) Resistor Sn (S1, S2, S3, S4, S5, S6) Sense terminal Vsen (Vse1, Vse2, Vse3, Vse4, Vse5, Vse6) Sense voltage Isn (Is1, Is2, Is3, Is4, Is5, Is6) Sense current θn (θ1, θ2, θ3, θ4, θ5, θ6) Temperature X, X1, X2, X3, X4, X5, X6 Characteristic line

Claims (9)

In a power conversion device having a power conversion unit that converts power supplied from a power source and outputs the power to an output device, and a control unit that drives and controls a switching element group constituting the power conversion unit,
Each switching element of the switching element group includes a sense terminal that outputs a sense current;
Connect a resistor to the sense terminal,
The control unit is incorporated in the power conversion unit, and obtains a recording medium for recording a correlation between the sense current and a sense voltage applied to both ends of the resistor, and a detected detection voltage according to the correlation. And a device control means for controlling an operating state of the output device based on the sense current.   2. The power conversion according to claim 1, wherein when the output device is a rotating machine, the device control unit controls one or both of the torque and the rotation speed of the output device according to the sense current. apparatus.   3. The power conversion device according to claim 1, further comprising an overcurrent control unit that performs control for protecting the switching element group when the sense voltage to be detected becomes the sense current outside a predetermined range. .   The power converter according to claim 3, wherein the overcurrent control unit performs control to stop driving of the switching element group, or performs control to reduce driving of the switching element group.   The overcurrent control unit performs control to reduce driving of the switching element group when the sense current exceeds a normal limit value, and further stops driving of the switching element group when the sense current exceeds an allowable value. The power conversion device according to claim 4, wherein:   The correlation between the sense current and the sense voltage is recorded on the recording medium corresponding to one or both of a gate voltage and a temperature applied to a target switching element. 5. The power conversion device according to claim 5.   7. The control unit according to claim 1, wherein the control unit inputs one or both of the gate voltage and the temperature, and specifies the sense current based on the input information. Power converter.   8. The power conversion device according to claim 1, wherein information on a characteristic line indicating a correlation between the sense current and the sense voltage is recorded on the recording medium.   The power converter according to any one of claims 1 to 8, further comprising a notification unit configured to notify an external device of information related to control performed by the device control unit and the overcurrent control unit.

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