JP2023106845A - power converter - Google Patents

Abstract

Kind Code: A1 In a power conversion device in which boost load factors of boost voltages generated by a plurality of boost converters are independently controlled, erroneous detection of a failure of a current sensor is suppressed. A power converter includes a battery, first and second reactors, first and second boost converters, a plurality of current sensors, and a controller that controls the first and second boost converters. The controller controls a first boost load factor of the first boost converter set according to the temperature of the first boost converter and a second boost load factor of the second boost converter set according to the temperature of the second boost converter. A distribution ratio map including the distribution ratio of the boost load factor for each combination of . The controller selects distribution ratios corresponding to the current first and second boost load factors from the distribution ratio map, and converts the current values measured by two of the plurality of current sensors to the selected distribution ratio. A failure of any one of the plurality of current sensors is detected by correcting and comparing them. [Selection drawing] Fig. 2

Description

The present invention relates to power converters.

For example, a power converter installed in a hybrid vehicle or the like has a plurality of boost converters that boost power supplied from a battery, and reactors that are arranged between the battery and each boost converter. This type of power conversion device detects a failure of the current sensor when the variation width of the reactor current measured by the current sensor is smaller than a predetermined value (see Patent Document 1, for example).

JP 2016-119770 A

When detecting a failure of the current sensor by monitoring the fluctuation range of the reactor current, a predetermined monitoring period is required, and the boost converter cannot be switched to the control at the time of failure of the current sensor until the failure is detected. . On the other hand, in a power conversion device that can independently change the boost load factor of the boost voltage generated by a plurality of boost converters according to overheating of each boost converter, the current sensors can When detecting a failure, the current value changes according to the change in the boost load factor. Therefore, even when the current sensor is normal, if the difference in the current value becomes large due to the difference in the boost load factor, there is a possibility that the current sensor failure is erroneously detected.

In view of the above problem, it is an object of the present invention to suppress erroneous detection of a failure of a current sensor in a power conversion device in which boost load factors of boost voltages generated by a plurality of boost converters are independently controlled.

In order to achieve the above object, a power converter according to an embodiment of the present disclosure includes a battery, a first boost converter and a second boost converter that boost power supplied from the battery, the first boost converter and the a control device that controls a second boost converter; a first reactor provided between the battery and the first boost converter; and a second reactor provided between the battery and the second boost converter. , a plurality of current sensors provided in a current path between the first reactor and the first boost converter and a current path between the second reactor and the second boost converter; Boosting for each combination of a first boost load factor of the first boost converter set according to the temperature and a second boost load factor of the second boost converter set according to the temperature of the second boost converter a distribution ratio map including distribution ratios of the load factors, wherein the control device selects the distribution ratios corresponding to the current first boost load factor and the second boost load factor from the distribution ratio map, and A failure of one of the plurality of current sensors is detected by correcting and comparing current values measured by two of the plurality of current sensors according to the selected distribution ratio. .

According to the present embodiment, it is possible to suppress erroneous detection of a failure of a current sensor in a power converter in which the boost load factors of boost voltages generated by a plurality of boost converters are independently controlled.

It is a block diagram showing an example of a power converter concerning a 1st embodiment. 2 is a functional block diagram showing an example of a control device 20 of FIG. 1; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.

[Configuration of the first embodiment]
FIG. 1 is a block diagram showing an example of a power converter according to the first embodiment. Although not particularly limited, the power conversion device 10 shown in FIG. 1 is mounted, for example, in a drive system of an electric vehicle or a hybrid vehicle. Power conversion device 10 includes control device 20, battery BAT, system main relays SMR1 and SMR2, booster circuit 30, capacitor C1, inverter 40, and motor generators MG1 and MG2.

The positive terminal of battery BAT is connected to the positive input terminal of booster circuit 30 via system main relay SMR1. The negative terminal of battery BAT is connected to the negative input terminal of booster circuit 30 via system main relay SMR2. Battery BAT supplies power to booster circuit 30 via system main relays SMR1 and SMR2.

Boost circuit 30 has capacitor C2, reactors L1 and L2, boost converters PC1 and PC2, current sensors A1A, A1B and A2, and temperature sensors T1 and T2. Capacitor C2 is connected between the positive input terminal and the negative input terminal of booster circuit 30 . Reactor L1 is connected between the positive input terminal of boost circuit 30 and the input terminal of boost converter PC1. Reactor L2 is connected between the negative input terminal of boost circuit 30 and the input terminal of boost converter PC2.

The configurations of boost converters PC1 and PC2 are similar to each other. Boost converter PC1 includes switching element S1 and diode D1 connected in parallel between the positive output terminal and the input terminal, and switching element S2 and diode D2 connected in parallel between the input terminal and the negative terminal. have. Boost converter PC2 includes switching element S3 and diode D3 connected in parallel between the positive output terminal and the input terminal, and switching element S4 and diode D4 connected in parallel between the input terminal and the negative terminal. have. Boost converters PC<b>1 and PC<b>2 boost the power supplied from battery BAT and supply the boosted power to inverter 40 .

The switching elements S1-S4 are, for example, IGBTs (Insulated Gate Bipolar Transistors), and are controlled by the control device 20 to operate. Positive output terminals of boost converters PC<b>1 and PC<b>2 are connected to each other and to a positive input terminal of inverter 40 . The negative terminals of boost converters PC1 and PC2 are connected to the negative terminal of battery BAT and to the negative terminal of inverter 40 via system main relay SMR2.

Current sensors A1A and A1B are respectively provided in current paths between reactor L1 and the input terminal of boost converter PC1. Current sensor A1A measures reactor current IL1 flowing through reactor L1, and outputs the measured reactor current IL1 to controller 20 as reactor current value IL1A. Current sensor A1B measures reactor current IL1 flowing through reactor L1, and outputs measured reactor current IL1 to controller 20 as reactor current value IL1B.

Current sensor A2 is provided in a current path between reactor L2 and the input terminal of boost converter PC2. Current sensor A2 measures a reactor current IL2 flowing through reactor L2, and outputs the measured reactor current IL2 to control device 20 as a reactor current value IL2. For example, current sensors A1A and A1B do not allow reactor current IL1 to flow when a failure occurs, and current sensor A2 does not allow reactor current IL2 to flow when a failure occurs. Reactor current values IL1A, IL1B, and IL2 are hereinafter also simply referred to as current values IL1A, IL1B, and IL2.

Temperature sensor T1 is arranged at a position (for example, near switching elements S1 and S2) where the ambient temperature of boost converter PC1 can be measured. The temperature sensor T1 outputs the measured temperature to the controller 20 as a temperature signal TC1. Temperature sensor T2 is arranged at a position (for example, near switching elements S3 and S4) where the ambient temperature of boost converter PC2 can be measured. The temperature sensor T2 outputs the measured temperature to the controller 20 as a temperature signal TC2.

Capacitor C1 is connected between a common positive output terminal and a common negative terminal of boost converters PC1 and PC2 to smooth the boost voltage generated by boost converters PC1 and PC2. The smoothed boosted voltage is used as the input voltage of inverter 40 .

The output of inverter 40 is connected to motor generators MG1 and MG2. For example, motor generators MG1 and MG2 are used for driving a vehicle, and rotation of output shafts of motor generators MG1 and MG2 is transmitted to wheels of the vehicle.

For example, the control device 20 may be an ECU (Electronic Control Unit) for controlling the booster circuit 30 . The control device 20 controls the inverter 40 according to, for example, the amount of depression of the accelerator or the target torque determined from the vehicle speed. At least one of motor generators MG1 and MG2 controlled by inverter 40 is driven to drive the vehicle. When the vehicle decelerates, control device 20 may control inverter 40 to perform regenerative braking by at least one of motor generators MG1 and MG2, and charge battery BAT with the obtained regenerative electric power.

Based on current value IL1A (or IL1B) and current value IL2 from boost circuit 30, controller 20 outputs control signals CNT1 and CNT2 for setting the boost voltage to a target value to boost converters PC1 and PC2, respectively. Switching elements S1-S4 of boost converters PC1 and PC2 operate according to control signals CNT1 and CNT2, respectively, to generate boost voltages.

For boost control of booster circuit 30, reactor current IL1 may be measured by one of current sensors A1A and A1B, and reactor current IL2 may be measured by current sensor A2. However, by measuring the reactor currents IL1 and IL2 with the three current sensors A1A, A1B and A2, it is possible to detect failure of any one of the current sensors A1A, A1B and A2 at high speed. On the other hand, if one current sensor is provided to measure each of the reactor currents IL1 and IL2, failure of any one of the current sensors means, for example, that the fluctuation range of the reactor currents IL1 and IL2 has become smaller than a predetermined position. must be detected by monitoring When monitoring the variation width of the reactor currents IL1 and IL2, it is difficult to detect a failure at high speed.

Further, control device 20 controls the boost load factor of the boost voltage generated by boost converter PC1 according to the temperature indicated by temperature signal TC1 from temperature sensor T1. Further, control device 20 controls the boost load factor of the boost voltage generated by boost converter PC2 according to the temperature indicated by temperature signal TC2 from temperature sensor T2. As a result, for example, when the ambient temperature of the boost converter PC1 (or PC2) exceeds a predetermined threshold temperature, the boost load factor of the boost converter PC1 (or PC2) exceeding the threshold temperature is set to the limit value LMT1 (or LMT1 shown in FIG. 2). LMT2). Thereby, a further temperature rise of boost converter PC1 (or PC2) can be suppressed.

Control device 20 obtains the power distribution ratio of boost converters PC1 and PC2 based on limit values LMT1 and LMT2 set in boost converters PC1 and PC2. Then, control device 20 detects failure of any of current sensors A1A, A1B, and A2 using the obtained power distribution ratio. Further, when control device 20 detects a failure in any one of current sensors A1A, A1B, and A2, control device 20 causes boost converters PC1 and PC2 to stop boosting operations. The control of boost converters PC1, PC2 by controller 20 and the detection of failures of current sensors A1A, A1B, A2 will be described in detail in FIG.

When the vehicle in which the power conversion device 10 is mounted has an engine, the output shafts of the motor generators MG1 and MG2 are connected to a power conversion unit such as a planetary gear mechanism, and the output shaft of the engine is connected to the power conversion unit. good too. Thus, control device 20 can cause the vehicle to run by at least one of the rotation of the output shafts of motor generators MG1 and MG2 and the rotation of the output shaft of the engine. Further, control device 20 may control the driving of engine ENG and inverter INV1 according to the state of charge of battery BAT to control the charging of battery BAT by the power generated by at least one of motor generators MG1 and MG2. good.

[Functional block diagram of control device]
FIG. 2 is a functional block diagram showing an example of the control device 20 of FIG. 1. As shown in FIG. Control device 20 has a boost output limiting unit 21 of boost converter PC1, a boost output limiting unit 22 of boost converter PC2, a distribution ratio calculation unit 23, and a diagnostic detection unit . Each function of the control device 20 may be realized by a control program executed by the control device 20, or may be realized by hardware such as an FPGA (Field-Programmable Gate Array). Furthermore, each function of the control device 20 may be realized by cooperating software and hardware.

When the temperature of boost converter PC1 indicated by temperature signal TC1 from temperature sensor T1 indicates overheating, boost output limiting unit 21 changes limit value LMT1 of the boost load factor of boost converter PC1 according to the temperature. Similarly, when the temperature of boost converter PC2 indicated by temperature signal TC2 from temperature sensor T2 indicates overheating, boost output limiting unit 22 changes limit value LMT2 of the boost load factor of boost converter PC2 according to the temperature. . Control device 20 controls the driving force (that is, boost load factor) of each of boost converters PC1 and PC2 according to limit values LMT1 and LMT2 set by boost output limiting units 21 and 22, respectively.

For example, the limit values LMT1 and LMT2 are changed from 0% to 100% with the preset upper limit value of the driving force being 100%. When the temperature of boost converter PC1 exceeds a predetermined temperature, boost output limiting unit 21 limits the driving force of boost converter PC1 by gradually lowering limit value LMT1 as the temperature rises. When the temperature of boost converter PC2 exceeds a predetermined temperature, boost output limiting unit 22 limits the driving force of boost converter PC2 by gradually lowering limit value LMT2 as the temperature rises.

Note that current values IL1A and IL1B measured by current sensors A1A and A1B decrease in accordance with the limitation of the driving force of boost converter PC1. Current value IL2 measured by current sensor A2 decreases in accordance with the limitation of the driving force of boost converter PC2. Therefore, when using the current values IL1A, IL1B, and IL2 to correctly detect a failure in any one of the current sensors A1A, A1B, and A2, it is necessary to determine the failure in consideration of the limit values LMT1 and LMT2. A method of determining failure of any one of the current sensors A1A, A1B, and A2 in consideration of the limit values LMT1 and LMT2 will be described later.

Boost output limiting unit 21 (22) may calculate limit value LMT1 (LMT2) from the temperature based on a formula representing the relationship between limit value LMT1 (LMT2) and the temperature of boost converter PC1 (PC2). Alternatively, boost output limiter 21 (22) may obtain limit value LMT1 (LMT2) from the temperature based on a table showing the relationship between limit value LMT1 (LMT2) and the temperature of boost converter PC1 (PC2). .

The distribution ratio calculator 23 has a distribution ratio map that indicates the distribution ratio X:Y for each combination of the limit values LMT1 and LMT2 at predetermined increments. The distribution ratio calculator 23 selects the distribution ratio X:Y corresponding to the current limit values LMT1 and LMT2 obtained by the boost output limiters 21 and 22 from the distribution ratio map, and performs diagnostic detection of the selected distribution ratio X:Y. Output to unit 24 . Note that the distribution ratio map may be provided outside the control device 20 .

In the example shown in FIG. 2, the distribution ratio calculator 23 calculates the distribution ratio X:Y from the distribution ratio map according to the limit value LMT1=80% and the limit value LMT2=20% obtained by the boost output limiters 21 and 22. = 4:1. Although the distribution ratio map shown in FIG. 2 shows 25 distribution ratio patterns with five limit values LMT1 and LMT2 in increments of 20%, the increments of the limit values LMT1 and LMT2 are not limited to 20%.

The diagnosis detection unit 24 utilizes the fact that the current value of the failed current sensor (either A1A, A1B, or A2) becomes zero to determine the difference between the current value of the normal current sensor and the current value of the failed current sensor. A current sensor failure is detected when the difference is greater than a predetermined value. In other words, the difference between the current values of two normal current sensors is within a predetermined value.

However, in this embodiment, the limit values LMT1, LMT2 of the boost converters PC1, PC2 are changed independently of each other. For this reason, when the distribution ratio X:Y is other than "1:1", the difference between the current values of the two current sensors becomes large even when the current sensors are normal, and there is a risk of erroneous detection of failure. Therefore, as will be described below, the diagnosis detection unit 24 detects a failure of any one of the current sensors A1A, A1B, A2 in consideration of the limit values LMT1, LMT2.

The diagnostic detection unit 24 acquires current values IL1A, IL1B, and IL2 from the current sensors A1A, A1B, and A2, respectively. Diagnosis detection unit 24 turns on flag 1 when the absolute value ABS of the difference between current values IL1A and ILIB exceeds 30 A (amperes).

Diagnosis detection unit 24 calculates the product of current value IL1A and ratio Y/X based on distribution ratio X:Y from distribution ratio calculation unit 23 . The diagnostic detection unit 24 turns on the flag 2 when the absolute value ABS of the difference between the calculated product and the current value IL2 exceeds 30A. The diagnostic detection unit 24 calculates the product of the current value IL1B and the distribution ratio Y/X. Diagnosis detection unit 24 turns on flag 3 when the absolute value ABS of the difference between the calculated product and current value IL2 exceeds 30A.

The threshold value (30A) for turning on flags 1, 2, and 3 is an example. Thresholds for turning on the flags 1, 2, and 3 may be determined according to the characteristics of the booster circuit 30. FIG. Note that the judgment formulas for the flags 2 and 3 shown in the diagnostic detection unit 24 in FIG. 2 may be obtained by multiplying the current value IL2 by the ratio X/Y instead of multiplying the current values IL1A and IL1B by the ratio Y/X.

Diagnosis detection unit 24 detects a failure of current sensor A1A when flag 1 and flag 2 are turned on. Diagnosis detection unit 24 detects a failure of current sensor A2 when flag 2 and flag 3 are turned on. Diagnosis detection unit 24 detects a failure of current sensor A1B when flag 1 and flag 3 are turned on.

Here, since the current values IL1A and IL1B change according to the common limit value LMT1, the current values IL1A and IL1B are compared without considering the distribution ratio X:Y. On the other hand, current values IL1A, IL1A and current value IL2 change according to limit values LMT1 and LMT2, respectively. Therefore, the comparison of the current values IL1A and IL2 and the comparison of the current values IL1B and IL2 are performed in consideration of the distribution ratio X:Y.

The ratio Y/X becomes smaller as "X" of the distribution ratio X:Y is larger than "Y". Therefore, in the formula shown in the diagnosis detection unit 24, the normal values of the currents IL1A and IL1B, which are relatively large when the limit value is LMT1>LMT2, can be corrected to match the normal value of the current value IL2. . Similarly, the ratio Y/X increases as the "X" of the distribution ratio X:Y is smaller than the "Y". Therefore, in the formula shown in the diagnosis detection unit 24, the normal values of the currents IL1A and IL1B, which are relatively small when the limit value is LMT1<LMT2, can be corrected to match the normal value of the current value IL2. can.

Therefore, even if the current value changes independently according to the switching of the limit values LMT1 and LMT2 when the boost converters PC1 and PC2 overheat, the failure of any of the current sensors A1A, A1B and A2 can be detected correctly. . In other words, when boost converters PC1 and PC2 overheat, it is possible to suppress excessive detection of a failure in any one of current sensors A1A, A1B and A2. As a result, deterioration of the running performance of the vehicle can be suppressed even though the current sensors A1A, A1B, and A2 are not malfunctioning.

When the diagnostic detection unit 24 detects a failure in any one of the current sensors A1A, A2, and A1B, the control device 20 fixes the switching elements S1 and S3 to the ON state and fixes the switching elements S2 and S4 to the OFF state. . As a result, booster circuit 30 switches to a so-called upper-arm ON state in which the DC voltage output from battery BAT is supplied to inverter 40 without being boosted.

Here, the upper arm shows switching element S1 and diode D1 and switching element S3 and diode D3. The lower arm shows switching element S2 and diode D2 and switching element S4 and diode D4.

Further, when the diagnosis detection unit 24 detects a failure in any one of the current sensors A1A, A2, and A1B, the control device 20 notifies the upper control device of the failure of the current sensor. Note that the diagnosis detection unit 24 determines that the current sensors A1A, A2, and A1B are normal when the flags 1, 2, and 3 are other than the three patterns described above.

When a common limit value is used for boost converters PC1 and PC2, for example, if the limit value is set to 20% due to overheating of boost converter PC2, the limit value of boost converter PC1 that is not overheated is also set to 20%. set. As a result, the output performance of the booster circuit 30 is reduced to 20% of normal without overheating.

In contrast, in this embodiment, for example, even if limit value LMT2 is set to 20% due to overheating of boost converter PC2, limit value LMT1 is set to 80%. At this time, the output performance of the booster circuit 30 can be reduced to 50% of the normal time without overheating. As a result, the output performance of the booster circuit 30 can be improved by 30% compared to the case of using a common limit value, and the running performance of the vehicle can be improved.

In the power conversion device 10 shown in FIG. 1, the current value IL1 of the reactor L1 is measured by two current sensors A1A and A1B, and the current value IL2 of the reactor L2 is measured by one current sensor A2. . However, power converter 10 may measure current value IL1 of reactor L1 with one current sensor A1A and measure current value IL2 of reactor L2 with two current sensors A2.

As described above, in this embodiment, even if the current value changes independently according to the switching of the limit values LMT1 and LMT2 when the boost converters PC1 and PC2 overheat, the failure of any one of the current sensors A1A, A1B and A2 can be detected correctly. can be detected. In other words, when boost converters PC1 and PC2 overheat, it is possible to suppress excessive detection (that is, erroneous detection) of a failure in any one of current sensors A1A, A1B and A2. As a result, deterioration of the running performance of the vehicle can be suppressed even though the current sensors A1A, A1B, and A2 are not malfunctioning.

In addition, by independently controlling the limit values in the boost converters PC1 and PC2, the output performance of the boost circuit 30 can be improved compared to the case where a common limit value is used, thereby improving the running performance of the vehicle. be able to.

Although the embodiments for carrying out the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and improvements are possible without departing from the spirit of the present invention. is.

REFERENCE SIGNS LIST 10 power conversion device 20 control device 21, 22 boost output limiter 23 distribution ratio calculator 24 diagnostic detector 30 booster circuit 40 inverter A1A, A1B, A2 current sensor BAT battery C1, C2 capacitors CNT1, CNT2 control signals D1, D2, D3, D4 Diode IL1, IL2 Reactor current ILIA, IL1B, IL2 Reactor current value L1, L2 Reactor LMT1, LMT2 Limit value MG1, MG2 Motor generator PC1, PC2 Boost converter S1, S2, S3, S4 Switching element SMR1, SMR2 System main Relay T1, T2 Temperature sensor TC1, TC2 Temperature signal

Claims (1)

a battery;
a first boost converter and a second boost converter for boosting power supplied from the battery;
a control device that controls the first boost converter and the second boost converter;
a first reactor provided between the battery and the first boost converter;
a second reactor provided between the battery and the second boost converter;
a plurality of current sensors provided on a current path between the first reactor and the first boost converter and a current path between the second reactor and the second boost converter;
A first boost load factor of the first boost converter that is set according to the temperature of the first boost converter, and a second boost load factor of the second boost converter that is set according to the temperature of the second boost converter. and a distribution ratio map containing the distribution ratio of the boost load factor for each combination of
The controller selects the distribution ratio corresponding to the current first boost load factor and the second boost load factor from the distribution ratio map, and the current values measured by two of the plurality of current sensors. is corrected according to the selected distribution ratio and compared to detect failure of any one of the plurality of current sensors.

Images