CN115051562A - Drive control device for controlling power conversion device - Google Patents
Drive control device for controlling power conversion device Download PDFInfo
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- CN115051562A CN115051562A CN202210192518.4A CN202210192518A CN115051562A CN 115051562 A CN115051562 A CN 115051562A CN 202210192518 A CN202210192518 A CN 202210192518A CN 115051562 A CN115051562 A CN 115051562A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Power Conversion In General (AREA)
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Abstract
A drive control device (1) is provided with a command value calculation unit (30), and the command value calculation unit (30) controls active drive control units (10 and 20) that perform drive control of switching elements. The active drive control units (10, 20) control the rate of change of the current flowing through the switching elements in accordance with the first command values (DHr1 and DLr1) during a first period from the start of turning on of the switching elements to be turned on, and control the rate of change of the current flowing through the switching elements in accordance with the second command values (DHr2 and DLr2) during a second period subsequent to the first period. A command value calculation unit (30) controls second command values (DHr2 and DLr2) on the basis of the temperatures of the 2 switching element units.
Description
Technical Field
The present disclosure relates to a drive control device that controls a power conversion device.
Background
As a technique for reducing the loss accompanying the switching of the power switching element included in the power conversion device, there is active drive control. This technique is disclosed in patent document 1, for example.
Documents of the prior art
Patent document
Patent document 1: japanese patent No. 5186095
Disclosure of Invention
Problems to be solved by the invention
However, in the technique disclosed in patent document 1, variations occur in the timing of switching the gate drive resistance or the drive current of the power switching element or in the drive current of the power switching element due to accuracy errors of electrical components such as a voltage detector for measuring the gate voltage or the like and a switching unit for the gate drive resistance. Therefore, in the power conversion apparatus including the upper power switching element and the lower power switching element connected in series, the reduction amount of the on-loss differs between the upper power switching element and the lower power switching element. Therefore, the temperatures of the power switching elements become unbalanced. As a result, the lifetime of the power switching element that generates much heat may be shortened. Further, when the power switching elements are designed with a margin on the premise of temperature imbalance, there is a problem that the power conversion device cannot sufficiently exhibit the performance.
The present disclosure has been made in view of the above-described problems, and an object of the present disclosure is to suppress the amount of heat generation of each switching element unit and equalize the amount of heat generation of each switching element unit in a power conversion device including 2 switching element units connected in series.
Means for solving the problems
A drive control device for controlling a power conversion device according to one aspect controls a power conversion device including 2 switching element units connected in series, the 2 switching element units each including a switching element and a diode connected in antiparallel with the switching element, the drive control device including a command value calculation unit for controlling an active drive control unit for performing drive control of the switching element, the active drive control unit controlling a rate of change of a current flowing through a target switching element, which is a switching element to be turned on, among the switching elements included in the 2 switching element units in accordance with a first command value during a first period from start of turning on of the target switching element, and controlling a rate of change of a current flowing through the target switching element in accordance with a second command value during a second period subsequent to the first period, the command value calculation unit controls the second command value based on the temperatures of the 2 switching element units, and controls the first command value to a predetermined value regardless of the temperatures.
A drive control device for controlling a power conversion device according to another aspect controls a power conversion device including 2 switching element units connected in series, wherein each of the 2 switching element units includes a switching element and a diode connected in antiparallel with the switching element, the drive control device includes a command value calculation unit that controls an active drive control unit that performs drive control of the switching element, the active drive control unit controls a rate of change of a current flowing through a target switching element among the switching elements included in the 2 switching element units according to a first command value during a first period from start of on of the target switching element, which is a switching element to be turned on, and controls a rate of change of a current flowing through the target switching element according to a second command value during a second period subsequent to the first period, when the target switching element is a switching element included in one of the 2 switching element units having a lower temperature, the command value calculation unit decreases the second command value to be output to the active drive control unit.
In addition, as another aspect, a drive control device for controlling a power conversion device, wherein the drive control device includes 2 switching element units connected in series, each of the 2 switching element units includes a switching element and a diode connected in antiparallel with the switching element, and the drive control device includes a command value calculation unit for controlling an active drive control unit for performing drive control of the switching element, the active drive control unit controls a rate of change of a current flowing through a target switching element among the switching elements included in the 2 switching element units in accordance with a first command value during a first period from start of turning on of the target switching element, which is a switching element to be turned on, and controls a rate of change of a current flowing through the target switching element in accordance with a second command value during a second period subsequent to the first period, the command value calculation unit controls the second command value based on the temperature difference between the 2 switching element units.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present disclosure, in the power conversion apparatus including 2 switching element units connected in series, it is possible to reduce switching loss in each switching element unit and equalize the amounts of heat generation of each switching element unit, thereby achieving a reduction in the failure rate and equalization of the element life due to the temperature of the switching element units.
Drawings
Fig. 1 is a circuit diagram showing a configuration of a power conversion device including a drive control device according to an embodiment.
Fig. 2 is a waveform diagram showing an operation example of the active drive control in the embodiment.
Fig. 3 is a block diagram showing a configuration of a first example of the instruction value calculation unit in the embodiment.
Fig. 4 is a waveform diagram showing an operation example of the embodiment adopting the first example.
Fig. 5 is a block diagram showing a part of the configuration of a second example of the instruction value calculation unit.
Fig. 6 is a block diagram showing a part of the configuration of a third example of the instruction value calculation unit.
Detailed Description
Embodiments of the present invention are described below with reference to the drawings.
Fig. 1 is a circuit diagram showing a configuration of a power conversion device 100 including a drive control device 1 according to an embodiment. In the power conversion device 100, the upper switching element section 110 is connected between the high-potential power supply line 101 and the output line 103. The high potential power supply line 101 is connected to the positive electrode of a dc power supply not shown. The output line 103 is connected to a load not shown. The lower switching element portion 120 is connected between the low-potential power supply line 102 and the output line 103. The low potential power supply line 102 is connected to the negative electrode of the dc power supply.
In this way, in the power conversion apparatus 100, the upper switching element unit 110 and the lower switching element unit 120 are connected in series between the high-potential power supply line 101 and the low-potential power supply line 102. The power conversion device 100 supplies power to a load connected to the output line 103 via the upper switching element unit 110 and the lower switching element unit 120 connected in series.
The upper switching element section 110 includes an upper power switching element 111. The lower switching element portion 120 includes a lower power switching element 121. The upper power switching element 111 and the lower power switching element 121 are MOSFETs (Metal Oxide Semiconductor Field Effect transistors) respectively. The upper power switching element 111 and the lower power switching element 121 are each formed of a wide bandgap semiconductor element such as SiC or GaN. An upper diode 112 is connected in reverse parallel to the upper power switching element 111. A lower diode 122 is connected in reverse parallel to the lower power switching element 121.
The temperature detector 131 detects the temperature STa1 of the upper switching element unit 110. The temperature detector 132 detects the temperature STa2 of the lower switching element portion 120.
A drive command DHa for the upper power switching element 111 and a drive command DLa for the lower power switching element 121 are supplied to the drive control device 1 from a higher-level device not shown. The drive control device 1 is a device that performs drive control of the upper power switching element 111 and the lower power switching element 121 based on the drive commands Dha and DLa, the temperature STa1 of the upper switching element unit 110, and the temperature STa2 of the lower switching element unit 120.
As shown in fig. 1, the drive control device 1 includes an upper active drive control unit 10, a lower active drive control unit 20, and a command value calculation unit 30.
The upper active drive control unit 10 is a device that outputs the gate voltage Vg that turns on the upper power switching element 111 and the gate voltage Vg that turns off the upper power switching element 111 to the upper power switching element 111, either one of them, in accordance with the drive command DHa. The lower active drive control unit 20 is a device for selectively outputting the gate voltage Vg for turning on the lower power switch element 121 and the gate voltage Vg for turning off the lower power switch element 121 to the lower power switch element 121 in accordance with the drive command DLa.
In the present embodiment, when the upper active drive control unit 10 turns on the upper power switching element 111, the period after the start of the turning on is divided into the initial mode 1 (i.e., the first period) and the subsequent mode 2 (i.e., the second period). The upper active drive control unit 10 controls the gate voltage Vg supplied to the upper power switching element 111 in each of the mode 1 and the mode 2. Here, for example, when the upper power switching element 111 is turned on, the pattern 2 is a period after the time when the reverse recovery is started in the lower diode 122. When the upper power switching element 111 is turned on, the upper power switching element 111 is an example of the target switching element.
More specifically, the first command value DHr1 corresponding to the pattern 1 and the second command value DHr2 corresponding to the pattern 2 are supplied from the command value calculation unit 30 to the upper active drive control unit 10 as command values related to the rate of change dId/dt (i.e., time derivative) of the drain current Id flowing through the upper power switching element 111.
When the upper power switching element 111 is turned on, the upper active drive control unit 10 controls the gate voltage Vg supplied to the upper power switching element 111 in the pattern 1 so that the rate of change dId/dt of the drain current Id flowing through the upper power switching element 111 follows the first command value DHr 1. In the mode 2, the upper active drive control unit 10 controls the gate voltage Vg supplied to the upper power switching element 111 so that the rate of change dId/dt of the drain current Id flowing through the upper power switching element 111 follows the second command value DHr 2.
Similarly, the first command value DLr1 corresponding to the pattern 1 and the second command value DLr2 corresponding to the pattern 2 are supplied from the command value calculation unit 30 to the lower active drive control unit 20 as command values relating to the rate of change of the drain current Id flowing through the lower power switching element 121. When the lower active drive control unit 20 turns on the lower power switching element 121, the gate voltage Vg supplied to the lower power switching element 121 is controlled in accordance with the first command value DLr1 in mode 1. In the mode 2, the lower active drive control unit 20 controls the gate voltage Vg supplied to the lower power switching element 121 in accordance with the second command value DLr 2. When the lower power switching element 121 is turned on, the lower power switching element 121 is an example of a target switching element.
The command value calculation unit 30 controls the upper active drive control unit 10 and the lower active drive control unit 20. More specifically, the command value calculation unit 30 is a device that calculates each command value for the upper switching element unit 110 and the lower switching element unit 120 based on the temperature STa1 of the upper switching element unit 110 and the temperature STa2 of the lower switching element unit 120.
Before describing the function of the command value calculation unit 30 in detail, the active drive control performed in the present embodiment will be described with reference to fig. 2. Fig. 2 shows waveforms of respective sections when the upper power switching element 111 is turned on with the lower power switching element 121 turned off.
When the drive command DHa is on to instruct the upper power switching element 111 to be turned on, the upper active drive control unit 10 starts the active drive control corresponding to the pattern 1 using the command value DHr regarding the rate of change of the drain current Id flowing through the upper power switching element 111 as the first command value DHr 1. That is, the upper active drive control unit 10 controls the gate voltage Vg supplied to the upper power switching element 111 in accordance with the first command value DHr 1.
Various methods are possible for controlling the gate voltage Vg. In a preferred embodiment, the gate drive resistors corresponding to the first command value DHr1 supplied from the command value calculation unit 30 are selected from the plurality of types of gate drive resistors provided corresponding to the various first command values DHr1, and the selected gate drive resistors are inserted into the input path of the gate voltage Vg in the upper power switching element 111. In another preferred embodiment, a plurality of types of current sources having different current values for charging the gate capacitance of the power switching element are used instead of the gate drive resistor.
When the active drive control corresponding to the mode 1 starts, the gate voltage Vg of the upper power switch element 111 starts rising with a slight delay. When the gate voltage Vg exceeds the threshold voltage Vth of the upper power switching element 111, the drain current Id starts flowing through the upper power switching element 111.
Then, the drain current Id increases as the gate voltage Vg rises. The on-resistance of the upper power switching element 111 decreases as the gate voltage Vg increases, and the drain-source voltage Vds decreases. When the influence of the increase in the drain current Id of the upper power switching element 111 is larger than the influence of the decrease in the on-resistance of the upper power switching element 111, the drain-source voltage Vds stops decreasing and then rises.
In the lower switching element unit 120 as a return-side element, a return current If flows through the lower diode 122 from before the upper power switching element 111 starts to be turned on. In mode 1, the drain current Id starts to flow through the upper power switching element 111, and the drain current Id is supplied to the lower diode 122, whereby the return current If flowing through the lower diode 122 decreases. Then, the return current If soon becomes 0. In mode 1, lower diode 122 is forward-biased, and voltage Vf between both ends of lower diode 122 is maintained at a predetermined voltage value. The above is the operation in mode 1.
When the return current If of the lower diode 122 becomes 0, the upper active drive control unit 10 starts the active drive control corresponding to the mode 2. That is, the upper active drive control unit 10 uses the command value DHr regarding the rate of change of the current Id flowing through the upper power switching element 111 as the second command value DHr2, and controls the gate voltage Vg supplied to the upper power switching element 111 in accordance with the second command value DHr 2. Typically, the second instruction value DHr2 is set to a lower value than the first instruction value DHr 1.
Various methods are available for determining the timing of the transition from mode 1 to mode 2. In a preferred embodiment, the return current If flowing through the lower diode 122 is detected, and the mode 1 is shifted to the mode 2 when the return current If becomes 0. In another preferred embodiment, the gate voltage Vg of the upper power switching element 111 is detected, and when the gate voltage Vg reaches a predetermined value, it is considered that the return current If has become 0, and the mode 1 shifts to the mode 2. In another preferred embodiment, it is assumed that the return current If has become 0 and the mode 1 shifts to the mode 2 when a predetermined time has elapsed from the start of the on operation.
In mode 2, in the lower switching element unit 120 which is an element on the return side, the drain current Id flowing through the upper power switching element 111 is supplied to the lower diode 122, and the reverse recovery current If flows through the lower diode 122. The reverse recovery current If is a current that disappears the minority carrier accumulated in the lower diode 122 while being forward biased, and flows in a direction opposite to the direction in which the return current If flows.
The reverse recovery current If flowing through the lower diode 122 increases in the mode 2 and decreases after reaching the peak. After the reverse recovery current If starts to flow, the voltage (in this case, the reverse direction voltage) Vf between the terminals of the lower diode 122 rises with a slight delay. Then, the reverse direction voltage Vf becomes a reverse recovery surge voltage VAK.
The operation of turning on the upper power switching element 111 and the operation of turning on the lower power switching element 121 are the same as described above.
In the operation described above, in mode 1, by increasing the rate of change dId/dt of the drain current Id flowing through the upper power switching element 111, the on-loss in the upper power switching element 111 can be made small. In mode 2, by reducing the rate of change dId/dt of the drain current Id flowing through the upper power switching element 111, the reverse recovery surge voltage VAK generated in the lower diode 122 can be reduced. Therefore, in the active drive control, both reduction of the turn-on loss and suppression of the reverse recovery surge voltage VAK are achieved by making the first command value large and the second command value small.
However, when the characteristics of the upper active drive control unit 10 and the characteristics of the lower active drive control unit 20 differ (for example, differences in gate drive resistance or differences in the switching timing) due to manufacturing variations of elements constituting the power conversion device 100, the amount of heat generated by the upper switching element unit 110 and the amount of heat generated by the lower switching element unit 120 differ. In this case, the following problems occur: one of the upper switching element unit 110 and the lower switching element unit 120, which generates a larger amount of heat, is likely to be heated to a higher temperature, and is more likely to be damaged than the other, or has a shorter life.
Therefore, the command value calculation unit 30 in the present embodiment solves this problem by controlling the first and second command values DHr1 and DHr2 for the upper active drive control unit 10 and the first and second command values DLr1 and DLr2 for the lower active drive control unit 20 so that the temperature STa1 of the upper switching element unit 110 is the same as the temperature STa2 of the lower switching element unit 120.
Fig. 3 is a block diagram showing the configuration of a command value calculation unit 30a as a first example of the command value calculation unit 30 in the present embodiment. As shown in fig. 3, the command value calculation unit 30a stores the first reference value Dr1def as a first command value optimized so as to sufficiently reduce the on-loss in the upper power switching element 111 and the lower power switching element 121 in the mode 1. The command value calculation unit 30a stores the second reference value Dr2def as a second command value optimized so that the reverse recovery surge voltage VAK generated in the upper diode 112 and the lower diode 122 can be appropriately suppressed in the mode 2. The first reference value Dr1def is a value set according to the characteristics of the upper power switching element 111 and the lower power switching element 121, and may be set to 4kA/μ s, for example. The second reference value Dr2def is also set according to the characteristics of the upper power switching element 111 and the lower power switching element 121, but may be set to a value smaller than the first reference value Dr1def, for example, 2 kA/. mu.s.
In the present embodiment, the command value calculation unit 30a outputs the first reference value Dr1def as the first command value DHr1 for the upper active drive control unit 10 and the first command value DLr1 for the lower active drive control unit 20. That is, in the present embodiment, the command value calculation unit 30a keeps the first command values DHr1 and DLr1 corresponding to mode 1 constant regardless of the temperature STa1 of the upper switching element unit 110 and the temperature STa2 of the lower switching element unit 120.
On the other hand, the command value calculation unit 30a calculates the second command values DHr2 and DLr2 in the pattern 2 from the second reference value Dr2def as follows based on the temperature STa1 of the upper switching element unit 110 and the temperature STa2 of the lower switching element unit 120.
The subtractor 300 subtracts the temperature STa2 of the lower switching element unit 120 from the temperature STa1 of the upper switching element unit 110, and outputs the subtraction result. For example, when the temperature STa1 is higher than the temperature STa2, the subtractor 300 outputs a positive value. In the case where the temperature STa2 is higher than the temperature STa1, the subtractor 300 outputs a negative value. The PI operator 301 outputs an output signal obtained by applying the proportional element P and the integral element I to the subtraction result of the subtractor 300. When the output signal of PI calculator 301 exceeds a predetermined upper limit value LMH, upper and lower limit limiter 302 outputs upper limit value LMH. When the output signal of PI calculator 301 is lower than predetermined lower limit LML, upper and lower limit limiter 302 outputs lower limit LML. When the output signal of PI operator 301 is between upper limit LMH and lower limit LML, upper/lower limit limiter 302 outputs the output signal of PI operator 301. In this case, the upper limit LMH and the lower limit LML may be determined according to the loss or the temperature in the power switching element.
When the output signal of the upper/lower limiter 302 is positive, the upper limiter 303 outputs 0 to the adder 305. When the output signal of the upper/lower limiter 302 is negative, the upper limiter 303 outputs the output signal of the upper/lower limiter 302 to the adder 305. The adder 305 outputs a value obtained by adding the second reference value Dr2def to the output signal of the upper limiter 303 as a second command value DHr2 for the upper active drive control unit 10.
When the output signal of the upper/lower limiter 302 is positive, the lower limiter 304 outputs the output signal of the upper/lower limiter 302 to the subtractor 306. When the output signal of the upper/lower limit limiter 302 is negative, the lower limit limiter 304 outputs 0 to the subtractor 306. The subtractor 306 outputs a value obtained by subtracting the output signal of the lower limit limiter 304 from the second reference value Dr2def as the second command value DLr2 for the lower active drive control unit 20.
In the above configuration, when the temperature STa1 of the upper switching element unit 110 is higher than the temperature STa2 of the lower switching element unit 120, a value obtained by subtracting a positive value corresponding to the difference between the two temperatures from the second reference value Dr2def is output as the second command value DLr2 for the lower active drive control unit 20, and the second reference value Dr2def is output as the second command value DHr2 for the upper active drive control unit 10.
Conversely, when the temperature STa2 of the lower switching element unit 120 is higher than the temperature STa1 of the upper switching element unit 110, a value obtained by adding a negative value corresponding to the difference between the two temperatures to the second reference value Dr2def is output as the second command value DHr2 for the upper active drive control unit 10, and the second reference value Dr2def is output as the second command value DLr2 for the lower active drive control unit 20.
Thus, in the present embodiment, the following control is performed: the second command value corresponding to the lower one of the temperatures of the upper switching element unit 110 and the lower switching element unit 120 is reduced from the second reference value Dr2 def.
Fig. 4 is a waveform diagram showing an operation example of the power conversion device 100 in which the command value calculation unit 30a as the first example is employed as the command value calculation unit 30. Fig. 4 shows waveforms of respective sections when the upper power switching element 111 is turned on with the lower power switching element 121 off, as in fig. 2. Fig. 4 shows waveforms of the respective portions in a case where the temperature STa1 of the upper switching element portion 110 is lower than the temperature STa2 of the lower switching element portion 120 by broken lines.
As described above, in mode 1, the rate of change did/dt of the drain current Id of the upper power switching element 111 is made large, whereby the on-loss in the upper power switching element 111 can be reduced. In mode 2, the reverse recovery surge voltage VAK can be reduced by reducing the rate of change did/dt of the drain current Id of the upper power switching element 111.
Here, the reverse recovery surge voltage VAK is determined by the change rate dId/dt of the drain current Id of the upper power switching element 111 when the reverse recovery current If flowing through the lower diode 122 is 0. Therefore, the rate of change of current dId/dt in mode 1 is independent of the reverse recovery surge voltage VAK.
Therefore, in the present embodiment, the first command values DHr1 and DLr1 in the mode 1 are maintained at the first reference value Dr1def, which is an optimal value, regardless of the temperature STa1 of the upper switching element unit 110 and the temperature STa2 of the lower switching element unit 120. By this, the on-loss in the upper power switching element 111 is reduced.
Next, in mode 2, when the rate of change dId/dt of the drain current Id of the upper power switching element 111 on the on side becomes smaller, the switching time of the upper power switching element 111 becomes longer, and therefore the on loss increases. On the other hand, when the rate of change dId/dt of the drain current Id of the upper power switching element 111 becomes smaller, the reverse recovery surge voltage VAK generated in the lower diode 122 on the return side decreases. As described above, in mode 2, the turn-on loss in the upper power switching element 111 and the reverse recovery loss in the lower diode 122 are in a trade-off relationship in which one increases and the other decreases.
Here, for example, when the temperature STa1 of the upper switching element portion 110 is lower than the temperature STa2 of the lower switching element portion 120, it is preferable that the loss in the lower switching element portion 120 be smaller than the loss in the upper switching element portion 110. This is because, in this way, the amount of heat generation of the lower switching element portion 120 is reduced more than the amount of heat generation of the upper switching element portion 110, and the temperatures of both are close to each other.
Therefore, in this example, the second command value DHr2 for the upper active drive control unit 10 corresponding to the upper switching element unit 110 having a low temperature is decreased to the second command value DHr 2' (shown by a broken line).
Thus, the drain current Id and the drain-source voltage Vds of the upper power switching element 111 on the on side become a drain current Id 'and a drain-source voltage Vds' (shown as a broken line) having a more gradual waveform time gradient. As a result, the on-loss of the upper power switching element 111 increases.
On the other hand, in lower switching element unit 120 as the return side, voltage Vf between both ends of lower diode 122 and reverse recovery current If become voltage Vf 'between both ends and reverse recovery current If' (shown as a broken line) having a more gradual time gradient of waveform. As a result, the reverse recovery surge voltage VAK is reduced to the reverse recovery surge voltage VAK', and the reverse recovery loss is reduced.
Therefore, the amount of heat generation of the lower switching element unit 120 is reduced more than the amount of heat generation of the upper switching element unit 110, and the temperatures of the two are close to each other.
As described above, according to the present embodiment, in the power converter in which 2 switching element units are connected in series, it is possible to reduce the switching loss in each switching element unit and equalize the amounts of heat generation of each switching element unit, thereby achieving a reduction in the failure rate and equalization of the element life due to the temperature of the switching element unit.
Next, a second example of the instruction value calculation unit 30 will be described with reference to fig. 5. In the second example, the configuration in the section from the subtractor 300 to the PI operator 301 in the first example (fig. 3) is replaced with the configuration shown in fig. 5.
In the second example, the absolute value calculator 307 calculates the absolute value of the difference between the temperatures STa1 and STa2 obtained from the subtractor 300. The comparator 308 compares the absolute value calculated by the absolute value calculator 307 with a predetermined threshold thc. When the absolute value calculated by the absolute value calculator 307 is equal to or greater than the threshold thc, the comparator 308 outputs True (True). When the absolute value calculated by the absolute value calculator 307 is not equal to or greater than the threshold thc, the comparator 308 outputs False (False).
When the output signal of the comparator 308 is true, that is, when the absolute value of the difference between the temperatures STa1 and STa2 exceeds the threshold thc, the switch 309 outputs the output signal of the subtractor 300 to the PI operator 301. When the output signal of the comparator 308 is false, the switch 309 outputs 0 to the PI operator 301. The operation of the other part is the same as the first example.
According to the second example, when the difference between the temperature STa1 of the upper switching element unit 110 and the temperature STa2 of the lower switching element unit 120 is equal to or greater than the threshold thc, the command value calculation unit 30 adjusts the second command value DHr2 or DLr 2. Therefore, it is possible to prevent the second command value DHr2 or DLr2 from being frequently adjusted due to a slight difference between the temperature STa1 of the upper switching element unit 110 and the temperature STa2 of the lower switching element unit 120, and to stabilize the operation of the drive control device 1.
Next, a third example of the instruction value calculation unit 30 will be described with reference to fig. 6. In the third example, the configuration in the section from the subtractor 300 to the PI operator 301 in the first example (fig. 3) is replaced with the configuration shown in fig. 6.
In the third example, the maximum value calculator 310 compares the temperature STa1 of the upper switching element unit 110 with the temperature STa2 of the lower switching element unit 120, and outputs the higher temperature to the comparator 308. The comparator 308 compares the temperature output from the maximum value calculator 310 with a predetermined threshold thd. When the temperature output from the maximum value calculator 310 is higher than the threshold thd, the comparator 308 outputs true to the switch 309. When the temperature output from the maximum value calculator 310 is lower than the threshold thd, the comparator 308 outputs false to the switch 309. Here, the threshold thd may be set to 150 ℃.
When the output of the comparator 308 is true, the switch 309 outputs the output signal of the subtractor 300 to the PI operator 301. When the output of the comparator 308 is false, the switch 309 outputs 0 to the PI operator 301. The operation of the other portions is the same as in the first example.
According to the third example, when one of the temperature STa1 of the upper switching element section 110 and the temperature STa2 of the lower switching element section 120, specifically, the higher one of the temperatures STa1 and STa2 is equal to or higher than a certain threshold value, the command value calculation section 30 adjusts the second command value DHr2 or DLr 2. Therefore, it is possible to prevent the second command value DHr2 or DLr2 from being frequently adjusted while the temperature of each switching element does not affect the characteristics of the switching element despite the temperature difference between the upper switching element unit 110 and the lower switching element unit 120, and to stabilize the operation of the drive control device 1.
< modification example >
While one embodiment has been described above, the one embodiment may be modified as follows, for example.
(1) First modification example
The third example of the command value calculation unit (fig. 6) adjusts the second command value DHr2 or DLr2 when the higher temperature of the temperature STa1 of the upper switching element unit 110 and the temperature STa2 of the lower switching element unit 120 is higher than the threshold value thd. Alternatively, the third example of the command value calculation unit may adjust the second command value DHr2 or DLr2 when the temperature STa1 of one of the upper switching element unit 110 or the lower switching element unit 120, for example, the upper switching element unit 110 is higher than the threshold value thd.
(2) Second modification example
The instruction value calculation unit may combine the second example and the third example described above. That is, when one of the temperature STa1 of the upper switching element unit 110 and the temperature STa2 of the lower switching element unit 120 is higher than the threshold thc and the difference between the two temperatures is higher than the threshold thd, the second command value DHr2 or DLr2 is adjusted. According to this modification, the second command value DHr2 or DLr2 is adjusted only during a period in which the amount of heat generated by the upper switching element portion 110 and the amount of heat generated by the lower switching element portion 120 are large as a whole, the difference between the amounts of heat generated by the two is large, and the necessity of adjusting the amounts of heat generated is high. Therefore, the operation of the drive control device 1 becomes more stable.
(3) Third modification example
The present disclosure can also be applied to power conversion devices other than inverters such as DC/DC converters.
(4) Fourth modification example
In the above embodiment, the command value calculation unit 30 is provided in the drive control device 1 together with the upper active drive control unit 10 and the lower active drive control unit 20. Alternatively, a drive control device having the command value calculation unit 30 instead of the upper active drive control unit 10 and the lower active drive control unit 20 may be provided as a device independent of the power conversion device 100.
(5) Fifth modification example
In the above-described embodiments, the MOSFET is given as an example of the power switching element, but the power switching element is not limited thereto, and may be another power switching element such as an IGBT (Insulated Gate Bipolar Transistor), for example.
Description of the reference numerals
100: a power conversion device; 1: a drive control device; 101: a high potential power supply line; 102: a low potential power supply line; 103: an output line; 110: an upper switching element section; 120: a lower switching element section; 111: an upper power switching element; 112: an upper side diode; 121: a lower power switching element; 122: a lower diode; 131. 132: a temperature detector; 10: an upper active drive control unit; 20: a lower active drive control unit; 30. 30 a: an instruction value calculation unit; 300. 306: a subtractor; 301: a PI arithmetic unit; 302: an upper and lower limit limiter; 303: an upper limit limiter; 304: a lower limit limiter; 305: an adder; 307: an absolute value calculation unit; 308: a comparator; 309: a switch; 310: a maximum value calculation unit.
Claims (8)
1. A drive control device for controlling a power conversion device including 2 switching element units connected in series,
the 2 switching element sections respectively include a switching element and a diode connected in inverse parallel with the switching element,
the drive control device includes a command value calculation unit that controls an active drive control unit that controls the drive of the switching element,
the active drive control unit controls a rate of change of a current flowing through the target switching element in accordance with a first command value in a first period from start of turning on of the target switching element, which is a switching element to be turned on, among the switching elements included in the 2 switching element units, and controls a rate of change of a current flowing through the target switching element in accordance with a second command value in a second period subsequent to the first period,
the command value calculation unit controls the second command value based on the temperatures of the 2 switching element units, and controls the first command value to a predetermined value regardless of the temperatures.
2. A drive control device for controlling a power conversion device including 2 switching element units connected in series,
the 2 switching element sections respectively include a switching element and a diode connected in inverse parallel with the switching element,
the drive control device includes a command value calculation unit that controls an active drive control unit that controls the drive of the switching element,
the active drive control unit controls a rate of change of a current flowing through the target switching element in accordance with a first command value in a first period from start of turning on of the target switching element, which is a switching element to be turned on, among the switching elements included in the 2 switching element units, and controls a rate of change of a current flowing through the target switching element in accordance with a second command value in a second period subsequent to the first period,
when the target switching element is a switching element included in one of the 2 switching element units having a lower temperature, the command value calculation unit decreases the second command value to be output to the active drive control unit.
3. A drive control device for controlling a power conversion device including 2 switching element units connected in series,
the 2 switching element sections respectively include a switching element and a diode connected in inverse parallel with the switching element,
the drive control device includes a command value calculation unit that controls an active drive control unit that controls the drive of the switching element,
the active drive control unit controls a rate of change of a current flowing through the target switching element in accordance with a first command value in a first period from start of turning on of the target switching element, which is a switching element to be turned on, among the switching elements included in the 2 switching element units, and controls a rate of change of a current flowing through the target switching element in accordance with a second command value in a second period subsequent to the first period,
the command value calculation unit controls the second command value based on the temperature difference between the 2 switching element units.
4. The drive control apparatus according to claim 2 or 3,
the command value calculation unit controls the first command value to a predetermined value regardless of the temperature.
5. The drive control apparatus according to claim 3,
when the target switching element is a switching element included in one of the 2 switching element units having a lower temperature, the command value calculation unit decreases the second command value to be output to the active drive control unit.
6. The drive control device according to any one of claims 1 to 3,
the command value calculation unit adjusts the second command value when the difference between the temperatures of the 2 switching element units is equal to or greater than a certain threshold value.
7. The drive control device according to any one of claims 1 to 3,
the command value calculation unit adjusts the second command value when one of the temperatures of the 2 switching element units is equal to or higher than a certain threshold value.
8. The drive control device according to any one of claims 1 to 3,
the switching element comprises a wide bandgap semiconductor element.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2021036290A JP6992920B1 (en) | 2021-03-08 | 2021-03-08 | Drive control device for power converter |
| JP2021-036290 | 2021-03-08 |
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| CN115051562A true CN115051562A (en) | 2022-09-13 |
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| JP3614519B2 (en) * | 1995-07-25 | 2005-01-26 | 株式会社日立製作所 | Method and apparatus for driving insulated gate semiconductor device |
| JP2009071956A (en) | 2007-09-12 | 2009-04-02 | Mitsubishi Electric Corp | Gate drive circuit |
| JP5887220B2 (en) | 2012-07-04 | 2016-03-16 | 株式会社 日立パワーデバイス | Semiconductor module |
| WO2017150036A1 (en) | 2016-03-04 | 2017-09-08 | 富士電機株式会社 | Driving device for semiconductor elements |
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| JP6992920B1 (en) | 2022-01-13 |
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