JP2016093074A - Inverter system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter system capable of protecting all switch elements included in the inverter from overheating timely even without obtaining temperatures for overall switch elements.SOLUTION: An inverter system includes: an inverter; a first sensor part for detecting a temperature of one switch element; a second sensor part for detecting whether it is in a state where another switch exceeding a first temperature exists; and a control part that sets, if it is not in the aforementioned state, an upper limit load ratio at 100% for a detected temperature of the first temperature or less, and uses a control map with which to lower the upper limit load ratio from 100% proportionately with a temperature rise starting from a detected temperature exceeding the first temperature, or sets, if it is in the state, an upper limit load ratio at 100% for a detected temperature of a second temperature, or less, being lower than the first temperature, and uses a control map with which to lower the upper limit load ratio from 100% proportionately with a temperature rise starting from a detected temperature exceeding the second temperature.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a system including an inverter that supplies converted power to a load.

  In a power conversion device such as an inverter, a loss due to the operation of the element under a high voltage and a high current generates a large amount of heat. Therefore, the temperature of the element is monitored to protect it from thermal destruction.

  Patent Document 1 describes a temperature detection circuit that acquires a detection signal from a temperature sensor provided in each of a plurality of power supply circuits and performs control to stop the operation of the power supply circuit in which a temperature abnormality is detected. Yes.

  In Patent Document 2, the temperature is detected for each of a plurality of power devices constituting the inverter, and the output current of the inverter is limited based on whether or not the maximum temperature among the temperatures reaches the limit temperature. A control device for overheat protection is described.

JP 2008-014798 A JP 2001-169401 A

  In the inverter, a plurality of switching elements that share single-phase or multi-phase outputs are provided. When any one of the switch elements reaches a high temperature, all the switch elements constituting the functional unit of the inverter are subjected to overheat protection control all at once. However, in order to obtain the temperature over all the switch elements and control overheat protection, many expensive parts are required. For example, in a power converter, an insulating structure for insulating a weak power system circuit or a weak power system circuit from a high voltage system circuit is introduced. For example, the output of a temperature sensor arranged in the switch element is transmitted using photocoupler insulation or a high voltage structure. In this case, in order to transmit the measurement output to the control system circuit with sufficient accuracy for feedback of protection control (for example, accuracy in which the temperature measurement error is suppressed to within about 1 ° C.), it is necessary to suppress transmission delay distortion. Expensive parts that can be produced are required for each switch element.

  In view of the above problems, the present invention provides an inverter system capable of overheating protection of all switch elements in a timely manner without acquiring temperature over all switch elements included in the inverter.

  The first invention includes an inverter that drives a switch element to supply load power, a first sensor unit that detects a temperature of a predetermined one of the switch elements included in the inverter, and the inverter. A second sensor unit that detects whether or not a switch element that exceeds a first temperature other than the predetermined one switch element is in a state that exceeds a threshold value; A control unit that performs drive control of a switch element included in the inverter using the temperature detected by the first sensor unit as a control temperature, and the control unit detects that the detection result by the second sensor unit exceeds the threshold value. In the case of indicating not in a state, the upper limit of the load factor is set to 100% at the control temperature equal to or lower than the first temperature, and the temperature exceeding the first temperature is exceeded. The drive control is performed using the first control map, and the upper limit of the load factor is decreased from 100% as the temperature rises from the control temperature, and the detection result by the second sensor unit is in the state exceeding the threshold. In the case of showing, the upper limit of the load factor is set to 100% at the control temperature equal to or lower than the second temperature set lower than the first temperature, and from the control temperature exceeding the second temperature. Is characterized in that the drive control is performed using a second control map that reduces the upper limit of the load factor from 100% in response to a temperature rise.

  According to the first aspect, the temperature of only one predetermined switch element among the switch elements included in the inverter is detected by the first sensor unit, and the control unit acquires the detected temperature as the control temperature. For other switch elements, the second sensor unit detects whether there is a switch element that exceeds the first temperature, and the control unit acquires the detection result. Based on the acquired contents, the control unit uses the first control map to control the first temperature or less when any switch element other than the predetermined one switch element is equal to or lower than the first temperature. In the temperature, the upper limit of the load factor is set to 100%, and the drive control of each switch element is performed so that the upper limit of the load factor is decreased from 100% as the temperature rises from the control temperature exceeding the first temperature. I do. In addition, when the control unit indicates that there is a switch element that exceeds the first temperature in addition to the predetermined one switch element based on the acquired contents, The upper limit of the load factor is set to 100% at the control temperature equal to or lower than the second temperature set lower than the first temperature using the second control map, and the control exceeds the second temperature. The drive control of each switch element is performed so that the upper limit of the load factor is decreased from 100% according to the temperature rise from the service temperature. According to such an inverter system, even if a switch element other than the predetermined one switch element that is not a target for acquiring the temperature is in a state that requires overheat protection exceeding the first temperature, According to the control temperature, the load factor limiting control is performed from the second temperature lower than the first temperature. Thereby, all the switch elements can be protected from overheating in a timely manner without acquiring temperatures over all the switch elements included in the inverter.

  ADVANTAGE OF THE INVENTION According to this invention, even if it does not acquire temperature over all the switch elements with which an inverter is equipped, the inverter system which can carry out overheat protection of all the switch elements in a timely manner can be provided.

The circuit block diagram which shows the structure of the inverter system which concerns on embodiment of this invention The circuit block diagram which shows the structure of a part of inverter system which concerns on embodiment of this invention The graph explaining the principle of the load factor control which concerns on embodiment of this invention Graph explaining load factor control according to an embodiment of the present invention The graph explaining the modification of the load factor control which concerns on embodiment of this invention The graph explaining the other modification of the load factor control which concerns on embodiment of this invention The flowchart explaining operation | movement by the control part of the inverter system which concerns on embodiment of this invention.

  Hereinafter, embodiments will be described in detail with reference to FIGS.

[Inverter system configuration]

  FIG. 1 shows a configuration of an inverter system 10 according to the present embodiment. The inverter system 10 is provided in a vehicle such as an automobile, and includes an inverter 1, a step-up / down converter 2, a temperature information transmission unit 3, and a control unit 4, and supplies power to a load such as a motor M <b> 1. The temperature information transmission unit 3 transmits the detected temperature acquired for only one switch element in the inverter 1. Further, the temperature information transmission unit 3 detects whether or not there is a switch element having a temperature exceeding the threshold temperature for the other switch elements in the inverter 1 and transmits the detection result. Based on these pieces of information acquired from the temperature information transmission unit 3, the control unit 4 controls the load factor so that all the switch elements are overheat protected.

  The inverter 1 is a three-phase inverter that supplies load power to the motor M1. The inverter 1 includes a power conversion unit 1a and a drive unit 1b.

  The power conversion unit 1a includes switch elements S1 to S6 that perform UVW phase output. For example, switch element S1 is a U-phase upper arm element, switch element S2 is a V-phase upper arm element, switch element S3 is a W-phase upper arm element, switch element S4 is a U-phase lower arm element, and switch element S5 is a V-phase lower arm element. The element, switch element S6 is a W-phase lower arm element. The switch element S1, the switch element S2, and the switch element S3 are connected to the high potential side power supply line L1. The switch element S4, the switch element S5, and the switch element S6 are connected to the low potential side power supply line L2. The high potential side power supply line L1 outputs a DC voltage VH, and the low potential side power supply line L2 outputs a DC voltage VL. For example, VH = 300V and VL = −300V. Each of the switch elements S1 to S6 is composed of an anti-parallel circuit of an IGBT (Insulated Gate Bipolar Transistor) 101 and a free-wheeling diode 102, for example, as shown by the switch element S1 on behalf of FIG. As the switch element, an element using any switching element can be used in addition to an element using IGBT.

  The drive unit 1b drives the switch elements S1 to S6 of the power conversion unit 1a according to a control signal input from the control unit 4. The drive unit 1b drives the switch elements S1 to S6 by, for example, pulse width modulation (PWM) control, and generates three-phase AC power from the UVW phase in a waveform using the DC voltage VH and the DC voltage VL. Output. In the configuration of the switch element shown in FIG. 2, the switch element is driven by inputting a drive signal from the drive unit 1 b to the gate of the IGBT 101.

  The inverter system 10 may include an arbitrary number of such inverters. For example, when the motor M1 is a compressor motor and a motor M2 that is a pump motor is provided, the inverter system 10 may include an inverter corresponding to each motor. Further, for example, an inverter of a traveling motor connected to the step-up / down converter 2 may be included.

  The step-up / down converter 2 includes a switch element S11 and a switch element S12 that are bridge-connected between the high potential side power line L1 and the low potential side power line L2. The DC voltage (VH−VL) boosted from the high voltage battery is generated by the switching operation of the switch element S11 and the switch element S12 in combination with the separately connected coil and the high voltage battery. The generated voltage is supplied to the drive of the driving motor. Alternatively, a high voltage battery voltage is generated from the DC voltage (VH−VL), and the current is regenerated to the battery.

  The temperature information transmission unit 3 includes a temperature detection unit A4, temperature range detection units A1, A2, A3, A5, and A6, temperature detection units B1 and B2, and a determination unit 31. Hereinafter, a configuration including the temperature detection unit A4 as a first sensor unit, a combination of the temperature range detection units A1, A2, A3, A5, and A6 and the determination unit 31 may be described as a second sensor unit. In the inverter system 10 according to the present embodiment, unlike the configuration in which overheat protection is performed by detecting the temperature of each switching element in the inverter, the target for transmitting information on the detected temperature value itself in the inverter 1 is the first sensor. Only one of the switch elements S4 whose temperature is detected by the part, and the other switch elements S1, S2, S3, S5, S6 need to be overheat protected by the corresponding temperature range detection part of the second sensor part. A detection result indicating whether or not the temperature is within a certain temperature range is to be transmitted to the determination unit 31. Moreover, the determination part 31 of the 2nd sensor part is in the temperature range which requires overheat protection in switch element S1, S2, S3, S5, S6 from the detection result by each transmitted temperature range detection part. Whether or not exists is detected.

  The temperature detector A4 is provided corresponding to only one of the six switch elements of the inverter 1, detects the temperature of the combined switch element S4, and provides information on the value of the detected temperature. The data is transmitted to the control unit 4. For example, the temperature detection unit A4 can be configured to insulatively transmit the information of the value of the temperature detected by the switch element S4 by the temperature sensor to the subsequent stage using a photocoupler as a signal modulated by the modulator. The temperature sensor is composed of, for example, a thermal diode formed on the same semiconductor chip as the switch element S4, and outputs a forward voltage that changes according to the temperature according to a temperature coefficient of about 3 mV / ° C. as a temperature detection result. The photocoupler has a high-speed response characteristic using a PIN photodiode or the like as a light receiving element, and is driven by a modulation signal whose signal level is switched at high speed. As a modulation method, any method such as PWM and digital modulation is used. Since the transmission delay distortion is suppressed by the high-speed response characteristic and the signal waveform is accurately transmitted, the temperature measurement accuracy is high. The temperature detector A4 may be combined with any one of the six switch elements of the inverter 1, but here is combined with the switch element S4 of the lower arm. According to the temperature detection unit A4 combined with such a lower arm switch element, it is easy to accurately detect the temperature because noise is hardly mixed in the temperature detection result. Further, the high-speed isolated transmission described above may be performed using a switching transformer instead of the photocoupler.

  The temperature range detection units A1, A2, A3, A5, and A6 detect whether or not the temperatures of the individually combined switch elements exceed the threshold value and transmit the detected values to the determination unit 31. Here, the temperature range detectors A1, A2, A3, A5, and A6 are combined with the switch elements S1, S2, S3, S5, and S6 in this order.

  The basic configuration of the temperature range detection units A1, A2, A3, A5, and A6 will be described with reference to FIG. Each temperature range detection unit is representatively shown for the temperature detection unit A1, for example, the output voltage Vo of the temperature sensor 21 corresponding to the temperature of the switch element SW is a threshold temperature (first temperature described later (FIG. 3 to 6, the comparator 22 determines whether or not the reference voltage Vref corresponding to the output (corresponding to 100 ° C.) corresponds to the output), and the photocoupler 24 driven by the drive unit 23 determines the determination result. It can be set as the structure which carries out insulation transmission to. For example, the temperature sensor 21 is formed on the same semiconductor chip as the switch element SW to be combined. The configuration of the temperature sensor 21 is the same as the temperature sensor described for the temperature detector A4. The photocoupler 24 includes a light emitting diode 24a in the light emitting element on the input side and a phototransistor 24a in the light receiving element on the output side. The photocoupler 24 has a low-speed response characteristic by using the phototransistor 24a as the light receiving element, and a general-purpose product can be applied.

  The output of the photocoupler 24 is switched to open or short according to the input. The collector of the phototransistor 24b is pulled up by a resistor R, and the emitter of the phototransistor 24b is grounded. If the output voltage Vo of the temperature sensor 21 is equal to or lower than the reference voltage Vref, the comparator 22 outputs a low signal, and a current is caused to flow to the light emitting diode 24a by the driving unit 23, so that the output of the phototransistor 24b is short-circuited. A low signal t <b> 1 is input to the determination unit 31. If the output voltage Vo of the temperature sensor 21 exceeds the reference voltage Vref, the comparator 22 outputs a high signal, no current flows to the light emitting diode 24a by the drive unit 23, and the output of the phototransistor 24b is opened. Therefore, a high signal t 1 is input to the determination unit 31 via the resistor R. In this manner, the temperature range detection units A1, A2, A3, A5, and A6 output signals t1, t2, t3, t5, and t6 indicating detection results to the determination unit 31 in this order.

  The temperature detectors B1 and B2 detect the temperatures of the individually combined switch elements and transmit information on the detected temperature value to the controller 4. Here, the temperature detection unit B1 and the temperature detection unit B2 are combined with the switch element S11 of the buck-boost converter 2 and the switch element S12 of the buck-boost converter 2 in this order. The configuration of these temperature detection units B1 and B2 can be the same as that of the temperature detection unit A4. The temperature detection unit B1 outputs a signal t11 indicating the detection temperature of the switch S11, and the temperature detection unit B2 outputs a signal t12 indicating the detection temperature of the switch element S12 to the control unit 4, respectively.

  The determination unit 31 determines whether there is a switch element having a temperature exceeding the threshold from the detection results acquired from the temperature range detection units A1, A2, A3, A5, and A6, and the determination result is transmitted to the control unit 4. Transmit to. As shown in FIG. 1, the determination unit 31 is configured by, for example, an OR circuit, and the temperature of the switch element exceeds the threshold in the detection result input from the temperature range detection units A1, A2, A3, A5, and A6. Whether or not a detection result indicating “” is included is distinguished by binary values and output. Here, a state in which the detection results acquired from the temperature range detection units A1, A2, A3, A5, and A6 indicate that there is a switch element having a temperature that exceeds the threshold is defined as a threshold excess state. If the signals output from the temperature range detectors A1, A2, A3, A5, and A6 are t1, t2, t3, t5, and t6 in this order, the fact that the threshold value is exceeded indicates that the signals t1, t2, t3, t5, At least one of t6 corresponds to indicating that the temperature of the switch element exceeds the threshold value. When the signals t1, t2, t3, t5, and t6 indicate that the signal exceeds the threshold value, the determination unit 31 outputs a signal that is determined as either a high signal or a low signal as the output U1.

  In addition, about temperature range detection part A1, A2, A3, A5, A6, the temperature range detection part A1, A2, A3, A5, A6 and the determination part 31 are connected by connecting the output of each photocoupler mentioned above in series. Can be configured simultaneously, that is, the second sensor unit can be configured at a time. As shown in FIG. 2, instead of grounding the emitter of the phototransistor 24b of the temperature range detector A1, it is connected to the collector of the phototransistor 24b of the temperature range detector A2. Similarly, the phototransistors 24b of the temperature range detectors A1, A2, A3, A5, and A6 are sequentially connected in series. However, in FIG. 2, each configuration of the temperature range detection units A2, A3, A5, and A6 is the same as the temperature range detection unit A1 except that the pull-up resistor R is not provided. It is assumed that the same symbols are applied to the same graphic symbols as those of the range detection unit A1. When the emitter of the phototransistor 24b of the temperature range detection unit A6 connected to the end is grounded, the collector of the temperature range detection unit A1 at the head becomes the output terminal of the wired OR constituted by the entire series connection. The output of the wired OR does not become an input to the determination unit 31 in FIG. 1, but derives an output U1 of the determination unit 31. That is, the configuration of the wired OR includes the configuration of the determination unit 31. If any one of the temperature range detection units A1, A2, A3, A5, and A6 is open, the output is open as a whole series connection. If the said structure is used, it can transmit to the control part 4 by the output U1 of the said wired OR that it exists in the said threshold value exceeding state. In addition, the connection order of each temperature range detection part in the said serial connection may be arbitrary.

  In this way, the determination unit 31 can be configured at the same time by connecting a part of the temperature range detection units A1, A2, A3, A5, and A6 called photocoupler outputs in series. In this case, it is not necessary to separately prepare an OR circuit as the determination unit 31, and circuit simplification and cost reduction are possible.

  As described in FIG. 1, when an inverter corresponding to another device such as the motor M2 is provided, the same first sensor unit and second sensor unit as described above are provided corresponding to the inverter. be able to.

  The power sources of the temperature range detectors A1, A2, A3, A5, and A6 described above are provided on the input side (light emitting unit side) and output side (light receiving unit side) of the photocoupler by providing the photocoupler. It is electrically insulated. The power source on the output side of the photocoupler is a weak power voltage system. For example, a power source common to the control unit 4 or a power source prepared separately from the power source of the control unit 4 is used. The power supply on the input side of the photocoupler is a high voltage system, and is isolated from the regulator voltage obtained from the high potential side power supply line L1 and the low potential side power supply line L2 or from the above power source of the weak power voltage system by a switching transformer. Use the power source obtained. In addition, grounding is electrically insulated between the input side and the output side of the photocoupler. For example, signal grounding similar to that of the control unit 4 is used for grounding on the input side of the photocoupler, and grounding to the housing is used for grounding on the output side of the photocoupler, similarly to the inverter 1.

  Next, the control unit 4 will be described. The control unit 4 is configured by a microcomputer or an ASIC (Application Specific Integrated Circuit), and controls the operation of a device such as the inverter 1 based on an input from the temperature information transmission unit 3. When the operation of the inverter 1 is controlled, the control unit 4 generates waveform information of the drive signal generated by the drive unit 1b and instructs the drive unit 1b. The waveform information includes information indicating whether the state exceeds the threshold value input from the determination unit 31, and information indicating the temperature of the switch element S4 input from the temperature detection unit A4. Generated by modulation. Also in the drive unit 1b, electrical insulation is performed between the side connected to the control unit 4 and the high voltage side that generates the drive voltage. For the insulation, for example, a photocoupler or a switching transformer is used. Further, when the motor M1 is provided in the compressor of the passenger compartment air conditioner, a control signal from the outside of the control unit 4 such that an instruction according to the setting of the temperature and the air volume by the user is given from the outside of the control unit 4 Is also included in the waveform information. The control unit 4 controls the operation of the step-up / down converter 2 based on inputs from the temperature detection units B <b> 1 and B <b> 2 of the temperature information transmission unit 3. Below, the content which controls operation | movement of the inverter 1 is demonstrated.

  Here, with reference to FIG. 3, a basic control principle applied when the control unit 4 controls the inverter 1 will be described. The storage medium provided in the control unit 4 stores a control map that describes a load factor control curve that determines what upper limit of the load factor to drive all the switch elements according to the temperature of the switch elements. ing. The load factor is expressed as a ratio of allowable load power to the maximum rating of load power. FIG. 3 shows the concept of the load factor control curve. For example, the upper limit of the load factor is set to 100% at a temperature of the switch element of 100 ° C. or less, and the upper limit of the load factor at the temperature of the switch element exceeding 100 ° C. Is reduced from 100% as the temperature rises, and is 0% at T0 ° C. T0 is set to a temperature below the rated temperature of the switch element. In the temperature region where the upper limit of the load factor is limited, the control unit 4 performs overheat protection of the switch element.

  The inverter 1 has a plurality of switch elements such as switch elements S1 to S6. If the temperature of the switch elements S1 to S6 is individually detected to control the upper limit of the load factor, the load shown in FIG. 3 is applied to all the switch elements S1 to S6 when any one of the switch elements exceeds 100 ° C. The control for limiting the upper limit of the load factor may be started according to the rate control curve, and when the temperature becomes higher, the control may be performed based on the temperature of the switch element at the maximum temperature. As a result, all the switch elements S1 to S6 are kept below the rated temperature. However, if the temperature is detected for each switch element and the overheat protection of all the switch elements is performed, an expensive component that insulates and transmits information of the detected temperature value is required for the feedback system from each switch element. .

  Here, the control unit 4 recognizes the temperature only from the switch element S4, and controls all the switch elements according to the same load factor control curve based on the recognized temperature. When the switch elements S1 to S6 are actually driven, the temperature may be different for each switch element due to variations in temperature characteristics among the switch elements and differences in the heat radiation environment where the switch elements are placed. Since it is not possible to accurately specify the temperature of the switch elements other than the switch element S4, the above T0 ° C. is considered to be safe for all switch elements in consideration of the presence of switch elements having a temperature higher than that of the switch element S4. A difference ΔTm as a temperature margin is set between the rated temperature and the rated temperature so as to protect against overheating. For example, when the rated temperature is 150 ° C., T 0 [° C.] = 130 [° C.] is set, and a difference ΔTm of 20 ° C. is secured.

  In the following, it is assumed that the load factor control is performed by setting the load factor within the range below the upper limit of the load factor corresponding to each temperature for the entire temperature range covered by the load factor control curve. Call it. In addition, among the entire temperature range covered by the load factor control curve, the switch factor is driven by setting the load factor within the range below the upper limit of the load factor in the temperature range in which the upper limit of the load factor is reduced below 100%. Performing the control is called load factor limiting control.

  Next, with reference to FIG. 4, the concrete load factor control which the control part 4 performs in this embodiment by applying the basic principle of FIG. 3 is demonstrated.

  When the switch elements S1 to S6 are driven, one of the switch elements S1 to S6 may be overheated earlier than the other elements. In consideration of this, the difference ΔTm ° C. in FIG. 3 is a temperature margin that allows safe overheat protection from the viewpoint of the switch elements other than the hottest switch element among all the switch elements. When the detected temperature for the switch element S4 is 100 ° C., the switch element having a temperature higher than that has already exceeded 100 ° C. and has continued to rise in temperature without being limited by the load factor. Therefore, there is a possibility that the load factor restriction control for the switch element that is already overheated will be delayed, and that the temperature suppression of the high temperature element may not work as intended. In this case, the difference ΔTm ° C. needs to be set to a substantially larger value. As described above, it is not easy to set a temperature margin for performing reliable overheat protection.

  Therefore, as described above, the switch elements S1, S2, S3, S5, and S6 other than the switch element S4 are determined by the second sensor unit as to whether or not a switch element requiring overheat protection is in a state exceeding a threshold value. The control unit 4 associates the detection result with the load factor limiting control. Here, the temperature range of the switch element requiring overheat protection is set to a range exceeding 100 ° C. (first temperature). And the control part 4 switches and uses two types of control maps demonstrated below according to the information (output U1) acquired from the 2nd sensor part as the said control map. The control unit 4 uses the detected temperature of the switch element S4 acquired from the first sensor unit as the control temperature, and applies it to the temperature coordinates of these control maps when setting the upper limit of the load factor.

  As shown in FIG. 4, when the control unit 4 recognizes from the output U1 that all of the switch elements S1, S2, S3, S5, and S6 are 100 ° C. or less, the control corresponding to the load factor control curve f1 is performed. A first control map that is a map is used. The load factor control curve f1 is the same as the load factor control curve shown in the example of FIG. 3, and the upper limit of the load factor is 100% at 100 ° C. (first temperature) or less, exceeding 100 ° C. and 130 ° C. or less. In the temperature range, the upper limit of the load factor is determined to have a load factor limiting gradient that decreases from 100% to 0% as the temperature rises. The upper limit of the load factor may be decreased stepwise from 100% to 0%. The temperature of 130 ° C. is a temperature selected and set from a temperature range higher than the first temperature of 100 ° C. and lower than the rated temperature of the switch element of 150 ° C. The upper limit of the load factor is set to 0% at 130 ° C. Even if the switch element S4 first exceeds 100 ° C. among all the switch elements, the control unit 4 uses the first control map as long as the switch elements other than the switch element S4 do not exceed 100 ° C.

  The control unit 4 is a control map corresponding to the load factor control curve f2 when it is recognized from the output U1 that any one of the switch elements S1, S2, S3, S5, and S6 exceeds 100 ° C. Use the second control map. The load factor control curve f2 has an upper limit of the load factor of 100% at 85 ° C. (second temperature) or less, and the upper limit of the load factor is increased in a temperature range of 85 ° C. to 115 ° C. (third temperature). Accordingly, the load factor is limited to a gradient that decreases from 100% to 0%. The upper limit of the load factor may be decreased stepwise from 100% to 0%. The second temperature of 85 ° C. is a temperature set lower than the first temperature of 100 ° C. The third temperature of 115 ° C. is a temperature set higher than the first temperature of 100 ° C. and below the rated temperature of the switch element of 150 ° C. At 115 ° C., the upper limit of the load factor is set to 0%. Here, the difference 30 ° C. between 85 ° C. and 115 ° C. and the load factor limiting gradient are set to be equal to the difference between 100 ° C. and 130 ° C. and the load factor limiting gradient in the load factor control curve f1.

  From the state where all of the switch elements S1, S2, S3, S5, and S6 are 100 ° C. or less, the control unit 4 is in a state where any one of the switch elements S1, S2, S3, S5, and S6 exceeds 100 ° C. ( When it is recognized that the state has shifted to (exceeding threshold value), the control map to be used is switched from the first control map to the second control map. Further, the control unit 4 starts from a state in which any one of the switch elements S1, S2, S3, S5, and S6 exceeds 100 ° C. (threshold exceeded state), and all of the switch elements S1, S2, S3, S5, and S6 When recognizing that it has shifted to a state of 100 ° C. or lower, the control map to be used is switched from the second control map to the first control map.

  As described above, when controlling the load factor, the operation region on the load factor control curve is read based on the temperature of the switch element S4 recognized by the control unit 4. Therefore, for example, if the temperature of the switch element S4 is 90 ° C. when the use of the second control map is started, the upper limit of the load factor at 90 ° C. of the load factor control curve f2 is applied to drive all the switch elements. When the switch elements other than the switch element S4 exceed the first temperature of 100 ° C., the temperature of the switch element S4 always exceeds the second temperature of 85 ° C. defined in the load factor control curve f2. If the second temperature is determined, it is possible to ensure a state in which overheat protection is started for all the switch elements without any delay. As for the second temperature at which such load factor limiting control in the load factor control curve f2 starts, for example, the difference between the first temperature and the second temperature is caused by variations in the temperature characteristics of the switch elements and the heat radiation environment. What is necessary is just to determine so that the maximum temperature difference between the switch elements to be included may be included.

[Modification]
FIG. 5 shows an example of another load factor control curve f2 described in the second control map. The load factor control curve f2 does not apply the load factor limiting gradient of the load factor control curve f1, but is a load factor limiting gradient smaller than the load factor control curve f1 from 100% at 85 ° C. (second temperature). Thus, the upper limit of the load factor is reduced to 0% at 130 ° C. (third temperature).

  FIG. 6 shows still another example of the load factor control curve f2 described in the second control map. The load factor control curve f2 does not apply the load factor limiting gradient of the load factor control curve f1, but is a load factor limiting gradient smaller than the load factor control curve f1 from 100% at 85 ° C. (second temperature). Thus, the upper limit of the load factor is reduced to 0% at a rated temperature of 150 ° C. (third temperature).

[Operation of control unit]
Next, FIG. 7 shows a flowchart for explaining the load factor control procedure executed by the control unit 4. The control procedure is performed by a computer provided in the control unit 4 reading out and executing a program stored in the storage medium, or by hardware built in the control unit 4 inputting data to the storage medium as necessary. It is executed by performing an operation according to various input signals with accompanying output.

  First, in step S101, when the inverter 1 is in a state where the operation can be started by turning on the power source of the vehicle or the like, the control unit 4 includes a first control map and a load factor control curve corresponding to the load factor control curve f1. A second control map corresponding to f2 is read from the storage medium in advance. In the subsequent step S102, load factor control is first applied by applying the detected temperature of the switch S4 acquired from the first sensor unit to the first control map. Next, in step S103, the control unit 4 determines whether the input from the second sensor unit indicates that the detection results for the switch elements S1, S2, S3, S5, and S6 other than the switch element S4 exceed the threshold value. Determine whether. If it is determined in step S103 that the threshold value is exceeded, the process proceeds to step S104. If the threshold value is not exceeded in step S103, the process returns to step S103.

  In step S104, the control unit 4 starts load factor control in which the detected temperature of the switch S4 acquired from the first sensor unit is applied to the second control map. That is, the control unit 4 switches the control map to be used from the first control map to the second control map. In subsequent step S105, the control unit 4 determines whether the input from the second sensor unit indicates that the detection results for the switch elements S1, S2, S3, S5, and S6 other than the switch element S4 exceed the threshold value. Determine whether. If the threshold value is exceeded in step S105, the process returns to step S105. If the threshold value is not exceeded in step S105, the process returns to step S102. When returning from step S105 to step S102, the control unit 4 switches the control map to be used from the second control map to the first control map.

  Although not shown in the drawings, the flow ends when the inverter is not operated due to the vehicle power being turned off.

[Effects of the embodiment, etc.]
According to the present embodiment, the temperature of only one predetermined switch element S4 among the switch elements S1 to S6 included in the inverter 1 is detected by the first sensor unit, and the control unit 4 acquires the detected temperature as the control temperature. . And about other switch element S1, S2, S3, S5, S6, it is detected by the 2nd sensor part whether the switch element exceeding 1st temperature exists, and the control part 4 acquires the said detection result. To do. Based on these acquisition contents, when any switch element other than the switch element S4 is equal to or lower than the first temperature, the control unit 4 uses the first control map to set the control temperature equal to or lower than the first temperature. Drive control of each switch element is performed so that the upper limit of the load factor is 100% and the upper limit of the load factor is decreased from 100% as the temperature rises from the control temperature exceeding the first temperature. On the basis of these acquired contents, the control unit 4 indicates that the detection result by the second sensor unit indicates that there is a switch element exceeding the first temperature other than the switch element S4. 2 Using the control map, the upper limit of the load factor is set to 100% at the control temperature lower than the second temperature set lower than the first temperature, and the load from the control temperature exceeding the second temperature The drive control of each switch element is performed so that the upper limit of the rate is decreased from 100% as the temperature rises. According to such an inverter system, even if a switch element other than the switch element S4, which is not a target for acquiring the temperature by the control unit 4, is in a state that requires overheat protection exceeding the first temperature, According to the temperature, the load factor limiting control is performed from the second temperature lower than the first temperature.

  As described above, all the switch elements S1 to S6 can be overheat protected in a timely manner without acquiring the temperature over all the switch elements S1 to S6 included in the inverter 1. In addition, a configuration capable of high-speed transmission is used to insulate and transmit information on the value of the detected temperature by the first sensor unit, while whether or not the temperature of the switch element exceeds the threshold value of the first temperature in the second sensor unit. It is possible to use an inexpensive insulated transmission configuration that can transmit such information. That is, in order to perform overheat protection for all the switch elements S1 to S6 included in the inverter 1, the information fed back to the control unit 4 is subjected to isolated transmission that does not require high-speed transmission except for one switch element S4. Therefore, it is possible to provide an inverter system having an inexpensive configuration in which the number of use points of expensive parts for insulated transmission is suppressed.

  Conventionally, in the case of an inverter for a hybrid vehicle, for example, it has been necessary to prepare a large number of the above-mentioned expensive parts, such as 14 systems corresponding to all the switch elements shown in FIG. Conventionally, even when trying to simplify the configuration for transmitting detected temperature value information for each switch element, many external parts of a microcomputer such as a multiplexer and a latch circuit have been used. There was a problem that the mounting area of was enormous. According to this embodiment, since many of these components can be omitted, the mounting area of the components is reduced.

  The present invention is applicable to a system including an inverter as well as a vehicle system.

DESCRIPTION OF SYMBOLS 1 Inverter 1a Power conversion part 1b Drive part 2 Buck-boost converter 3 Temperature information transmission part 4 Control part 10 Inverter system 21 Temperature sensor 22 Comparator 23 Drive part 24 Photocoupler 24a Light emitting diode 24b Photodiode 31 Determination part 101 IGBT
102 Freewheeling diode A4 Temperature detection part A1, A2, A3, A5, A6 Temperature range detection part B1, B2 Temperature detection part f1, f2 Load factor control curve M1, M2 Motor R Resistors S1, S2, S3, S4, S5, S6, S11, S12 Switch elements t1, t2, t3, t4, t5, t6, t11, t12 Signal ΔTm Difference T0 Temperature Vref Reference voltage

Claims (1)

An inverter that drives the switch element to supply load power;
A first sensor unit that detects a temperature of a predetermined one of the switch elements included in the inverter;
A second sensor unit that detects whether or not a switch element included in the inverter is in a state exceeding a threshold value, which is a state in which a switch element exceeding a first temperature other than the predetermined one switch element exists. When,
A control unit that performs drive control of a switch element included in the inverter using the temperature detected by the first sensor unit as a control temperature, and
The controller is
When the detection result by the second sensor unit indicates that the threshold value is not exceeded, the upper limit of the load factor is set to 100% at the control temperature equal to or lower than the first temperature, and the first temperature The drive control is performed using the first control map, wherein the upper limit of the load factor is decreased from 100% according to the temperature rise from the control temperature exceeding
When the detection result by the second sensor unit indicates that the threshold value is exceeded, the upper limit of the load factor is set to 100 at the control temperature equal to or lower than the second temperature set lower than the first temperature. %, And from the control temperature exceeding the second temperature, the upper limit of the load factor is decreased from 100% as the temperature rises, and the drive control is performed using a second control map. Inverter system.

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