Power conversion device and program

Abstract

To provide a power converter capable of properly performing power transfer and heat generation by switching control of a switch unit.SOLUTION: A control unit 70 executes first switching control in a first period longer than a first switching period of a switch unit 21, and executes second switching control in a second period longer than the first switching period of the switch unit 21. The control unit 70 executes the first switching control so as to control an average power value that is a time average value of a transmitted power value in a prescribed period equal to or longer than a total period of the first period and the second period to a target average power value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power conversion device. , and programs Regarding. [Background technology]

[0002] Conventionally, electrical energy input from a power supply unit is converted into thermal energy by switching control of a switch unit included in a power conversion device, and the thermal energy is used to raise the temperature of the power supply unit. Patent Document 1 discloses a power conversion device that increases the amount of heat generated in the switch unit by lowering the gate voltage when the switch unit is turned on to increase the conduction loss of the switch unit, thereby raising the temperature of the power supply unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4665911 Summary of the Invention [Problem to be solved by the invention]

[0004] However, increasing the amount of heat generated by the switch unit reduces the amount of power transmitted from the power supply unit to the power supply target via the switch unit. If the transmitted power value is increased to avoid this reduction, the amount of heat generated by the switch unit increases, which can cause the switch unit to overheat.

[0005] The present invention has been made in view of the above-mentioned problems, and its main object is to provide a power conversion device that can appropriately perform power transmission and heat generation by switching control of a switch unit. , and programs The purpose is to provide [Means for solving the problem]

[0006] A first invention for solving the above problems is a power conversion device having an input terminal, an output terminal, and a switch unit, and transmitting power input from the input terminal to the output terminal by performing switching control of the switch unit, a request determination unit that determines whether or not there is a request to increase the amount of heat generated in the switch unit in response to the execution of the switching control; a control unit that, when it is determined that there is a request for an increase, alternately executes a first switching control for transmitting power from the input terminal to the output terminal and a second switching control in which the amount of heat generated by the switch unit is greater than the amount of heat generated by the switch unit due to execution of the first switching control; Equipped with The control unit performing the first switching control in a first period longer than one switching cycle of the switch unit, and performing the second switching control in a second period longer than one switching cycle of the switch unit; The first switching control is executed to control an average power value, which is a time average value of the power value transmitted from the input terminal to the output terminal during a specified period that is equal to or greater than the total period of the first period and the second period, to a target average power value.

[0007] When switching control of the switch unit that focuses on heat generation is executed, the transmitted power value will vary depending on the circumstances and will deviate from the target average power value. Here, the average transmitted power value over a period that includes the execution period of switching control that focuses on heat generation as well as the execution period of switching control that focuses on power transmission is set as the controlled variable, and the execution period of each switching control is set to be longer than one switching cycle. This makes it possible to increase the amount of heat generated by the switch unit while bringing the average transmitted power value closer to the target average power value.

[0008] In view of this point, in the first invention, when it is determined that there is a request to increase the amount of heat generated in the switch section, first switching control that focuses on power transmission and second switching control that focuses on heat generation are executed alternately.

[0009] The average power value is the time average value of the transmitted power value over a specified period equal to or greater than the sum of the first period during which the first switching control is executed and the second period during which the second switching control is executed. In this case, the first switching control is executed to control the average power value to the target average power value. For example, when the transmitted power value falls below the target average power value in the second period, the first switching control is executed so that the transmitted power value is greater than the target average power value in the first period. Also, for example, when the transmitted power value exceeds the target average power value in the second period, the first switching control is executed so that the transmitted power value is less than the target average power value in the first period. This makes it possible to increase the amount of heat generated in the switch unit while bringing the average power value transmitted from the input terminal to the output terminal closer to the target average power value.

[0010] A second invention is a power conversion device having an input terminal, an output terminal, and a switch unit, and transmitting power input from the input terminal to the output terminal by performing switching control of the switch unit, a request determination unit that determines whether or not there is a request to increase the amount of heat generated in the switch unit in response to the execution of the switching control; a control unit that, when it is determined that there is a request for an increase, executes a first switching control to set a gate voltage of the switch unit to a first voltage and a second switching control to set the gate voltage of the switch unit to a second voltage lower than the first voltage during a period in which the switch unit is turned on in one switching cycle of the switch unit; a thermal parameter acquisition unit that acquires a thermal parameter that is a heat amount generated in association with execution of the first switching control and the second switching control or a correlation value thereof; Equipped with The control unit If the acquired thermal parameter is lower than a target value, increasing a ratio of an execution period of the second switching control to an execution period of the first switching control; If the obtained thermal parameter exceeds the target value, the ratio is decreased.

[0011] In a second aspect of the present invention, when it is determined that there is a request to increase the amount of heat generated by the switch unit, a first switching control and a second switching control in which the gate voltage of the switch unit is lower than that of the first switching control are executed during a period in which the switch unit is turned on. The second switching control is executed in order to increase the amount of heat generated by the switch unit. In other words, the second switching control causes a larger conduction loss in the switch unit than the first switching control, and the amount of heat generated by the switch unit is larger.

[0012] In the second aspect of the present invention, the amount of heat generated in association with the execution of the first switching control and the second switching control or a heat parameter that is a correlation value thereof is acquired, and if the acquired heat parameter is below a target value, the ratio of the execution period of the second switching control to the execution period of the first switching control is increased. Increasing the ratio increases the amount of heat generated in the switch unit. On the other hand, if the acquired heat parameter exceeds the target value, the ratio is decreased. Decreasing the ratio decreases the amount of heat generated in the switch unit. This allows the amount of heat generated in the switch unit to be increased while approaching the target heat amount.

[0013] A third aspect of the present invention is a power conversion device having an input terminal, an output terminal, and a switch unit, and transmitting power input from the input terminal to the output terminal by performing switching control of the switch unit, a request determination unit that determines whether or not there is a request to increase the amount of heat generated in the switch unit in response to the execution of the switching control; a control unit that, when it is determined that there is a request for an increase, executes switching control to set a gate voltage of the switch unit to a specified voltage that is lower than that when it is determined that there is no request for an increase, during a period in which the switch unit is turned on within one switching cycle of the switch unit; a thermal parameter acquisition unit that acquires a thermal parameter that is a heat quantity generated in association with execution of the switching control or a correlation value thereof; Equipped with The control unit If the acquired thermal parameter is below a target value, reducing the specified voltage; If the acquired thermal parameter exceeds the target value, the specified voltage is increased.

[0014] In a third aspect of the present invention, when it is determined that there is a request to increase the amount of heat generated by the switch unit, switching control is executed to set the gate voltage of the switch unit to a specified voltage that is lower than when it is determined that there is no request to increase, during the period when the switch unit is turned on. In other words, when it is determined that there is a request to increase, the conduction loss of the switch unit is larger than when it is determined that there is no request to increase, and the amount of heat generated by the switch unit is larger.

[0015] In a third aspect of the present invention, the amount of heat generated in association with the execution of switching control or a thermal parameter that is a correlation value thereof is acquired, and if the acquired thermal parameter is below a target value, the specified voltage is reduced. Reducing the specified voltage increases the conduction loss of the switch unit, and the amount of heat generated in the switch unit. On the other hand, if the acquired thermal parameter exceeds the target value, the specified voltage is increased. Increasing the specified voltage reduces the conduction loss of the switch unit, and the amount of heat generated in the switch unit. This allows power to be transmitted from the input terminal to the output terminal, and the amount of heat generated in the switch unit can be increased while approaching the target amount of heat. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a configuration diagram of a power conversion device according to a first embodiment. [Figure 2] FIG. 3 is a functional block diagram of a control unit according to the first embodiment in a normal mode. [Figure 3] FIG. 4 is a functional block diagram of the control unit in a heat generation mode according to the first embodiment. [Figure 4] 4 is a timing chart showing the transition of the driving state of each switch according to the first embodiment. [Figure 5] 10 is a graph showing the relationship between transmitted power value and heat quantity. [Figure 6] 10 is a flowchart showing a processing procedure of a control unit. [Figure 7] 10 is a timing chart showing the transition of the transmitted power value and the amount of heat in a comparative example. [Figure 8] FIG. 3 is a circuit diagram of a gate voltage driver. [Figure 9] FIG. 10 is a functional block diagram of a control unit according to a second embodiment. [Figure 10] 10 is a timing chart showing the transition of the transmitted power value and the amount of heat according to the second embodiment. [Figure 11] 10 is a graph showing average power values and average amounts of heat in a heat generation mode. [Figure 12] FIG. 11 is a functional block diagram of a control unit according to a third embodiment. [Figure 13] 10 is a timing chart showing the transition of the driving state of each switch according to the third embodiment. [Figure 14] FIG. 4 is a diagram showing a current path during a reverse polarity period. [Figure 15] FIG. 11 is a functional block diagram of a control unit according to a fifth embodiment. [Figure 16] 10 is a timing chart showing the transition of the driving state of each switch according to the fifth embodiment. [Figure 17] FIG. 10 is a configuration diagram of a power conversion device according to a sixth embodiment. [Figure 18] FIG. 13 is a configuration diagram of a power conversion device according to a seventh embodiment. [Figure 19] FIG. 13 is a configuration diagram of a power conversion device according to an eighth embodiment. [Figure 20] FIG. 13 is a configuration diagram of a power conversion device according to a ninth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] First Embodiment A first embodiment of a power conversion device according to the present invention will now be described with reference to the drawings. The power conversion device of this embodiment is mounted on an electrically powered vehicle such as a plug-in hybrid vehicle or an electric vehicle.

[0018] As shown in FIG. 1, the power conversion system includes a storage battery 10, a power supply target 11, a first capacitor 12, a second capacitor 13, and a power conversion device 20.

[0019] The storage battery 10 supplies power to the power supply target 11 via the power conversion device 20. The storage battery 10 is a chargeable and dischargeable secondary battery, for example, a lithium ion storage battery.

[0020] The power conversion device 20 includes a first high potential side terminal CH1, a first low potential side terminal CL1, a second high potential side terminal CH2, a second low potential side terminal CL2, and a switch unit 21. In this embodiment, the first high potential side terminal CH1 and the first low potential side terminal CL1 correspond to input side terminals, and the second high potential side terminal CH2 and the second low potential side terminal CL2 correspond to output side terminals.

[0021] The switch section 21 includes a first full-bridge circuit 30, a second full-bridge circuit 40, and a transformer 50. The first full-bridge circuit 30 includes first to fourth switches Q1 to Q4. The second full-bridge circuit 40 includes fifth to eighth switches Q5 to Q8. In this embodiment, the first to eighth switches Q1 to Q8 are N-channel MOSFETs.

[0022] In the first full-bridge circuit 30, a first high potential side terminal CH1 is connected to the drains of the first switch Q1 and the third switch Q3. A drain of the second switch Q2 is connected to the source of the first switch Q1, and a drain of the fourth switch Q4 is connected to the source of the third switch Q3. A first low potential side terminal CL1 is connected to the sources of the second switch Q2 and the fourth switch Q4. A positive terminal of the storage battery 10 is connected to the first high potential side terminal CH1, and a negative terminal of the storage battery 10 is connected to the first low potential side terminal CL1. A first capacitor 12 is connected between the positive and negative terminals of the storage battery 10.

[0023] In the second full-bridge circuit 40, the drains of the fifth switch Q5 and the seventh switch Q7 are connected to a second high-potential side terminal CH2. The drain of the sixth switch Q6 is connected to a source of the fifth switch Q5, and the drain of the eighth switch Q8 is connected to a source of the seventh switch Q7. The second low-potential side terminal CL2 is connected to the sources of the sixth switch Q6 and the eighth switch Q8. The power supply target 11 and the second capacitor 13 are connected in parallel between the second high-potential side terminal CH2 and the second low-potential side terminal CL2.

[0024] The transformer 50 has a first coil 50a and a second coil 50b. A first end of the first coil 50a is connected to the source of a first switch Q1 and the drain of a second switch Q2, and a second end of the first coil 50a is connected to the source of a third switch Q3 and the drain of a fourth switch Q4. A first end of the second coil 50b is connected to the source of a fifth switch Q5 and the drain of a sixth switch Q6, and a second end of the second coil 50b is connected to the source of a seventh switch Q7 and the drain of an eighth switch Q8.

[0025] The first coil 50a and the second coil 50b are magnetically coupled to each other. When the potential of the first end of the first coil 50a becomes higher relative to the second end, an induced voltage is generated in the second coil 50b such that the potential of the first end is higher than the second end. On the other hand, when the potential of the second end of the first coil 50a becomes higher relative to the first end, an induced voltage is generated in the second coil 50b such that the potential of the second end is higher than the first end.

[0026] The power conversion system includes a first current sensor 60, a first voltage sensor 61, a second current sensor 62, a second voltage sensor 63, and a temperature sensor 64. The first current sensor 60 detects a first current I1 flowing through the first high potential side terminal CH1, and the first voltage sensor 61 detects a first voltage V1 which is the voltage between the first high potential side terminal CH1 and the first low potential side terminal CL1. Here, the first current I1 is positive when a discharging current flows to the storage battery 10, and negative when a charging current flows.

[0027] The second current sensor 62 detects the second current I2 flowing through the second high potential side terminal CH2, and the second voltage sensor 63 detects the second voltage V2, which is the terminal voltage between the second high potential side terminal CH2 and the second low potential side terminal CL2. Here, the second current I2 is considered positive when it flows from the second high potential side terminal CH2 to the drains of the fifth switch Q5 and the seventh switch Q7, and negative when it flows in the opposite direction.

[0028] The temperature sensor 64 detects the environmental temperature T. In this embodiment, the environmental temperature T is the temperature of an element to be heated. The element to be heated is, for example, the power converter 20 or the storage battery 10.

[0029] The detected values I1, V1, I2, V2, and T are input to a control unit 70 included in the power conversion device 20. The control unit 70 outputs a gate voltage Vg to the gate of each of the switches Q1 to Q8 based on the detected values I1, V1, I2, V2, and T, and performs switching control of each of the switches Q1 to Q8.

[0030] Next, the temperature rise control performed in this embodiment will be described. In this embodiment, the temperature rise control when power is transmitted from the storage battery 10 to the power supply target 11 via the power conversion device 20 will be described. In this case, the first full-bridge circuit 30 corresponds to an input-side full-bridge circuit, and by executing switching control of first to fourth switches Q1 to Q4 as input-side switches, converts a DC voltage input from the storage battery 10 into an AC voltage and applies it to the first coil 50a. Furthermore, the second full-bridge circuit 40 corresponds to an output-side full-bridge circuit, and by executing switching control of fifth to eighth switches Q5 to Q8 as output-side switches, converts an AC voltage output from the second coil 50b into a DC voltage and outputs it to the power supply target 11.

[0031] In the temperature rise control, if the ambient temperature T is higher than the set temperature, there is no request to increase the amount of heat generated by the switch due to the execution of switching control, and the normal mode is set. On the other hand, if the ambient temperature T is equal to or lower than the set temperature, there is a request to increase the amount of heat generated by the switch, and the heat generation mode is set.

[0032] 2 is a block diagram showing switching control in the normal mode performed by the control unit 70. The control unit 70 includes a first controller 82.

[0033] The first controller 82 includes a command current setting unit 71. The command current setting unit 71 includes a current calculation unit 72 and a minimum value selection unit 73.

[0034] The current calculation unit 72 calculates the command current I2f by dividing the target power value PW* by the second voltage V2, which is the voltage detected by the second voltage sensor 63. The sign of the command current I2f is defined the same as the sign of the second current I2.

[0035] The minimum value selection unit 73 selects, as the final command current Iref2, the command current I2f calculated by the current calculation unit 72 or the current command value I2*, whichever has a smaller absolute value. The current command value I2* is set to, for example, the upper limit value of the current value that can be flowed through the first full-bridge circuit 30. The command current Iref2 output from the minimum value selection unit 73 is limited to an upper limit value or a lower limit value by a first limiter 74.

[0036] The first controller 82 includes a current controller 75. The current controller 75 includes a current deviation calculation unit 76, a first feedback control unit 77, and a second limiter 78. The current deviation calculation unit 76 calculates a current deviation ΔI2 by subtracting the second current I2, which is the current detected by the second current sensor 62, from the command current Iref2 output from the first limiter 74.

[0037] The first feedback control unit 77 calculates the inter-port phase φ21 as a manipulated variable for feeding back the calculated current deviation ΔI2 to zero. In this embodiment, proportional-integral control using a positive feedback gain is executed as this feedback control. Note that the feedback control executed by the first feedback control unit 77 is not limited to proportional-integral control, and may be, for example, proportional-integral-derivative control.

[0038] The inter-port phase φ21 calculated by the first feedback control unit 77 is limited to an upper or lower limit by the second limiter 78. In this embodiment, the inter-port phase φ21 is set in the range of -90° to 90°. The sign of the inter-port phase φ21 indicates the direction of power transmission. However, in this embodiment, an example will be described in which power is transmitted in the direction from the first full-bridge circuit 30 to the second full-bridge circuit 40. For this reason, hereinafter, the inter-port phase φ21 is assumed to be a value in the range of 0° to 90°. The larger the inter-port phase φ21, the greater the power transmitted from the storage battery 10 to the power supply target 11.

[0039] The first controller 82 includes a PWM generating unit 79 and a gate voltage driving unit 80 .

[0040] The PWM generating unit 79 generates drive signals SD for each of the switches Q1 to Q8 based on the inter-port phase φ21 output from the second limiter 78, and outputs the drive signals SD to the gate voltage driving unit 80. The PWM generating unit 79 generates the drive signals SD for the first to fourth switches Q1 to Q4 to alternately turn on the set of the first and fourth switches Q1 and Q4 and the set of the second and third switches Q2 and Q3. The PWM generating unit 79 also generates the drive signals SD for the fifth to eighth switches Q5 to Q8 to alternately turn on the set of the fifth and eighth switches Q5 and Q8 and the set of the sixth and seventh switches Q6 and Q7. In this embodiment, one switching period Tsw for each of the switches Q1 to Q8 is the same. Furthermore, the duty ratio (=Ton / Tsw), which is the ratio of the on-period Ton to one switching period Tsw for each of the switches Q1 to Q8, is also the same value (e.g., 0.5). The PWM generating unit 79 generates the drive signals SD for each switch Q1 to Q8 so that the timing at which the fifth switch Q5 switches to the on state is advanced by the inter-port phase φ21 output from the second limiter 78 relative to the timing at which the first and fourth switches Q1 and Q4 switch to the on state.

[0041] Power is transferred from the storage battery 10 to the power supply target 11 under the condition that the first and fourth switches Q1 and Q4 are turned on and the fifth and eighth switches Q5 and Q8 are turned on, or the second and third switches Q2 and Q3 are turned on and the sixth and seventh switches Q6 and Q7 are turned on. The period during which power is transferred is a period during which the polarity of the voltage applied from the first full-bridge circuit 30 to the first coil 50a and the polarity of the voltage applied from the second full-bridge circuit 40 to the second coil 50b are the same.

[0042] On the other hand, when the first and fourth switches Q1 and Q4 are turned on and the fifth and eighth switches Q5 and Q8 are turned off, or when the second and third switches Q2 and Q3 are turned on and the sixth and seventh switches Q6 and Q7 are turned off, no power (active power) is transferred from the storage battery 10 to the power supply target 11. The period during which no power is transferred is a reverse polarity period during which the polarity of the voltage applied from the first full-bridge circuit 30 to the first coil 50a and the polarity of the voltage applied from the second full-bridge circuit 40 to the second coil 50b are reversed.

[0043] The gate voltage driver 80 outputs a gate voltage Vg to the gate of each of the switches Q1 to Q8 based on the input drive signal SD. In this case, the gate voltage driver 80 sets the gate voltage Von when turning on each of the switches Q1 to Q8 to a first on-voltage Vα that is equal to or higher than the threshold voltage Vth of each of the switches Q1 to Q8. When the first on-voltage Vα is input, each of the switches Q1 to Q8 is in a fully on state.

[0044] On the other hand, in the heat generation mode, the first switching control and the second switching control are executed alternately.

[0045] FIG. 3 shows a block diagram of the heat generation mode control performed by the control unit 70. The control unit 70 includes a first controller 82 and a second controller 83. The first controller 82 is a processing unit for performing first switching control. In the heat generation mode, the first controller 82 is the same as the first controller 82 shown in FIG. 2, except that the value input to the current calculation unit 72 is changed from the target power value PW* to the target average power value PWave*. Furthermore, the value input to the current deviation calculation unit 76 is changed from the second current I2 to the average current Iave2. The average current Iave2 is the time average value of the second current I2 over a specified period TK. The specified period TK is the sum of a first period TW1 during which the first switching control is performed and a second period TW2 during which the second switching control is performed. Each of the first period TW1 and the second period TW2 is longer than one switching cycle Tsw. The average current Iave2 is calculated by an average current calculation unit 76a. The current deviation calculation unit 76 subtracts the average current Iave2 from the command current Iref2 output from the first limiter 74 to calculate a current deviation ΔI2.

[0046] The second controller 83 is a processing unit for performing second switching control, and includes a heat generation controller 81, a PWM generation unit 79, and a gate voltage driver 80. The heat generation controller 81 stores a phase map MP. The phase map MP is correlation information that associates the ambient temperature T with the inter-port phase φ21, and is set so that the absolute value of the inter-port phase φ21 increases as the ambient temperature T decreases. The heat generation controller 81 sets the inter-port phase φ21 based on the ambient temperature T detected by the temperature sensor 64.

[0047] For example, the heat generation controller 81 sets the inter-port phase φ21 based on the ambient temperature T, thereby bringing the average unit heat energy HEave, which is the time average value of the unit heat energy HE over a specified period TK, closer to the target unit heat energy HE*. Here, the unit heat energy HE refers to the amount of heat [W] generated by the switch unit 21 per unit time due to switching control.

[0048] The PWM generating unit 79 generates drive signals SD for the switches Q1 to Q8 based on the inter-port phase φ21 set by the heat generation controller 81, similar to the PWM generating unit 79 in FIG.

[0049] The gate voltage driver 80 outputs a gate voltage Vg to the gates of the switches Q1 to Q8 based on the output drive signal SD. In the second switching control, the gate voltage driver 80 sets the gate voltage Von to a first on-voltage Vα when turning on the fifth to eighth switches Q5 to Q8. On the other hand, the gate voltage driver 80 sets the gate voltage Von to a second on-voltage Vβ (≧Vth) lower than the first on-voltage Vα when turning on the first to fourth switches Q1 to Q4.

[0050] That is, in the second switching control, the gate voltage Von when the first to fourth switches Q1 to Q4 are turned on is lower than when the first switching control is executed. When the second on-voltage Vβ is input, the first to fourth switches Q1 to Q4 are turned on half-on. The on-resistance of the switches in the half-on state is higher than the on-resistance of the switches in the full-on state. As a result, the conduction loss generated in the switches in the half-on state is higher than the conduction loss generated in the switches in the full-on state. As a result, the amount of heat generated in the first to fourth switches Q1 to Q4 in the second switching control is higher than the amount of heat generated in the first to fourth switches Q1 to Q4 in the first switching control.

[0051] Although FIG. 3 shows that the first controller 82 and the second controller 83 each include a PWM generating unit 79 and a gate voltage driving unit 80, the PWM generating unit 79 and the gate voltage driving unit 80 may be shared by the first controller 82 and the second controller 83.

[0052] The command current setting unit 71 sets the target average power value PWave*. The current calculation unit 72 calculates the command current I2f by dividing the target average power value PWave* by the second voltage V2. Then, the first feedback control unit 77 sets the inter-port phase φ21 so as to feed back the current deviation ΔI2 to 0, that is, so that the calculated average current Iave2 follows the command current Iref2. The average current Iave2 correlates with the average power value PWave, which is the time average value of the transmission power value PW over the specified period TK, and the command current Iref2 correlates with the target average power value PWave*. Therefore, by bringing the average current Iave2 closer to the command current Iref2, the average power value PWave can be brought closer to the target average power value PWave*.

[0053] Specifically, when the transmission power value PW in the second time period TW2 is smaller than the target average power value PWave*, the average current Iave2 becomes smaller than the command current Iref2. In this case, the first feedback control unit 77 sets the inter-port phase φ21 to be larger so that the average current Iave2 approaches the command current Iref2. This increases the transmission power value PW in the first time period TW1, allowing the average power value PWave to approach the target average power value PWave*. Furthermore, when the transmission power value PW in the second time period TW2 is larger than the target average power value PWave*, the average current Iave2 becomes larger than the command current Iref2. In this case, the first feedback control unit 77 sets the inter-port phase φ21 to be smaller so that the average current Iave2 approaches the command current Iref2. This decreases the transmission power value PW in the first time period TW1, allowing the average power value PWave to approach the target average power value PWave*.

[0054] 4 shows the transition of the drive states of the first and fifth switches Q1 and Q5 in the heat generation mode. Note that the drive state of the fourth switch Q4 is the same as the drive state of the first switch Q1, and the drive states of the second and third switches Q2 and Q3 are the same as the inverted drive state of the first switch Q1, so they are not shown here. Also, the drive state of the eighth switch Q8 is the same as the drive state of the fifth switch Q5, and the drive states of the sixth and seventh switches Q6 and Q7 are the same as the inverted drive state of the fifth switch Q5, so they are not shown here.

[0055] In Fig. 4, (A) shows the transition of switching control, (B) shows the transition of gate voltage Vg of the first switch Q1, and (C) shows the transition of main terminal voltage (drain-source voltage) Vds of the first switch Q1. Also, (D) shows the transition of gate voltage Vg of the fifth switch Q5, (E) shows the transition of main terminal voltage Vds of the fifth switch Q5, (F) shows the transition of main terminal currents (drain-source currents) Ids1 and Ids5 of the first and Q5 switches Q1 and Q5, and (G) shows the transition of conduction loss of the first switch Q1. In Fig. 4(F), the solid line shows the transition of main terminal current Ids1 of the first switch Q1, and the dashed line shows the transition of main terminal current Ids5 of the fifth switch Q5.

[0056] 4, the first switching control is performed during a first period TW1 from time t1 to time t2, and the second switching control is performed during a second period TW2 from time t2 to time t3. The first and second periods TW1 and TW2 are set to periods longer than one switching period Tsw of the first switch Q1. The first and second periods TW1 and TW2 may be set to the same period (e.g., 10 times one switching period Tsw) or may be set to different periods. When the periods are different, for example, the first period TW1 may be set to 5 times one switching period Tsw, and the second period TW2 may be set to 10 times one switching period Tsw.

[0057] In the first switching control, when turning on the first and fifth switches Q1 and Q5, the first on-voltage Vα is applied as the gate voltage Von. Therefore, during the on-period Ton when the first and fifth switches Q1 and Q5 are turned on, the voltage Vds between the main terminals of the first and fifth switches Q1 and Q5 becomes substantially zero. Therefore, in the first switching control, almost no conduction loss represented by the product of the voltage Vds between the main terminals and the currents Ids1 and Ids5 between the main terminals occurs.

[0058] On the other hand, in the second switching control, when turning on the first switch Q1, the second on-voltage Vβ (<Vα) is applied as the gate voltage Von. Therefore, during the on-period Ton when the first switch Q1 is turned on, the voltage Vds between the main terminals of the first switch Q1 becomes larger than the voltage Vds between the main terminals when the first switching control is performed, and the conduction loss generated in the first switch Q1 increases significantly. In this embodiment, due to the configuration shown in FIG. 8 described later, in order to set the gate voltage Von to the second on-voltage Vβ, the voltage Vds between the main terminals is set to the target value Vds*.

[0059] FIG. 5 shows the relationship between the power transmission value PW from the storage battery 10 to the power supply target 11 and the unit heat quantity HE generated in the first to fourth switches Q1 to Q4. In FIG. 5, the dashed-dotted line shows the above relationship when the heat generation period ratio represented by "TW2 / TK" is large, and the solid line shows the above relationship when the heat generation period ratio is small.

[0060] As shown by the dashed-dotted line in FIG. 5, when the heat generation period ratio is large, the larger the port-to-port phase φ21, the larger the unit heat quantity HE can be. However, when the port-to-port phase φ21 is increased, not only the unit heat quantity HE but also the power transmission value PW increases. Therefore, when controlling the unit heat quantity HE to the target unit heat quantity HE*, the power transmission value PW may greatly exceed the target average power value PWave*.

[0061] On the other hand, as shown by the solid line in Figure 5, when the heat generation period ratio is small, even if the inter-port phase φ21 is increased, the unit heat quantity HE remains small while the transmitted power value PW increases. In other words, the relationship between the unit heat quantity HE and the transmitted power value PW changes depending on the heat generation period ratio. In light of this, in this embodiment, the first switching control and the second switching control are performed alternately in the heat generation mode.

[0062] 6 shows the procedure of the process executed by the control unit 70. This process is executed repeatedly, for example, at a predetermined control period.

[0063] In step S10, the current command value I2* and the target average power value PWave* are set.

[0064] In step S11, the environmental temperature T detected by the temperature sensor 64 is acquired, and it is determined whether the acquired environmental temperature T is equal to or lower than a set temperature. In this embodiment, the process of step S11 corresponds to a "request determination unit."

[0065] If a negative determination is made in step S11, it is assumed that there is no request to increase the amount of heat generated, and the process proceeds to step S12. In step S12, the control mode is set to the normal mode, and the control shown in FIG. 2 is executed. On the other hand, if a positive determination is made in step S11, it is assumed that there is a request to increase the amount of heat generated, and the process proceeds to step S13. In step S13, the control mode is set to the heat generation mode, and the first switching control and the second switching control shown in FIG. 3 are executed alternately.

[0066] 7 shows the transition of the transmitted power value PW and the unit heat quantity HE in a comparative example. The comparative example is a control in which only the second switching control is executed out of the first and second switching controls.

[0067] In the comparative example, the length of the inter-port phase φ21 in the second switching control is set based on the ambient temperature T so that the unit heat quantity HE becomes the target unit heat quantity HE*. However, the transmitted power value PW is left to the discretion of the user. Therefore, for example, if the transmitted power value PW corresponding to the set inter-port phase φ21 is greater than the target power value PW*, the transmitted power value PW will greatly exceed the target power value PW*.

[0068] In contrast, in this embodiment, the first switching control and the second switching control are performed alternately. If the transmission power value PW in the second period TW2 in which the second switching control is performed is smaller than the target average power value PWave*, the transmission power value PW in the first period TW1 in which the first switching control is performed is made larger than the target average power value PWave*. Also, if the transmission power value PW in the second period TW2 is larger than the target average power value PWave*, the transmission power value PW in the first period TW1 is made smaller than the target average power value PWave*. This allows the average power value PWave to approach the target average power value PWave*.

[0069] Fig. 8 shows the circuit configuration of the gate voltage driver 80. In Fig. 8, the gate voltage driver 80 corresponding to the first switch Q1 will be described as an example. Note that the gate voltage driver 80 corresponding to the second to eighth switches Q2 to Q8 are the same as the gate voltage driver 80 corresponding to the first switch Q1, and therefore description thereof will be omitted.

[0070] The gate voltage driver 80 includes a charging resistor RC and a discharging resistor RD.

[0071] One end of the charging resistor RC is connected to the first power supply PS1 via the charging switch SWC, and the other end of the charging resistor RC is connected to the gate of the first switch Q1 via the charging / discharging path LA. One end of the discharging resistor RD is connected to the gate of the first switch Q1 via the charging / discharging path LA, and the other end of the discharging resistor RD is connected to the source of the first switch Q1 via the discharging switch SWD.

[0072] A drive signal SD corresponding to the first switch Q1 is input to the gate of the charge switch SWC, and an inverted signal SR of the drive signal SD is input to the gate of the discharge switch SWD by an inverter circuit CR. When the drive signal SD is an ON signal, the charge switch SWC is turned on and the discharge switch SWD is turned off. In this case, a power supply voltage for turning on the first switch Q1 is applied from the first power supply PS1 to the gate of the first switch Q1, and charge flows into the gate of the first switch Q1. As a result, the gate voltage Vg of the first switch Q1 becomes equal to or higher than the threshold voltage Vth, and the first switch Q1 is turned on.

[0073] On the other hand, when the drive signal SD is an OFF signal, the charge switch SWC is turned OFF and the discharge switch SWD is turned OFF. In this case, charge flows from the gate of the first switch Q1 to the source via the charge / discharge path LA and the discharge switch SWD. As a result, the gate voltage Vg of the first switch Q1 becomes less than the threshold voltage Vth, and the first switch Q1 is turned OFF.

[0074] The gate voltage driver 80 includes a series connection of a first voltage dividing resistor Rb1 and a second voltage dividing resistor Rb2 (corresponding to a "voltage detection unit"), which connects the drain and source of the first switch Q1.

[0075] The gate voltage driver 80 includes an operational amplifier CP, first to fifth resistors R1 to R5, a Zener diode DT, a changeover switch SWK, and an adjustment switch SWN.

[0076] The inverting input terminal of the operational amplifier CP is connected to the connection point of the first voltage divider resistor Rb1 and the second voltage divider resistor Rb2 via the first resistor R1. The voltage Vds across the main terminals of the first switch Q1 is divided by the first voltage divider resistor Rb1 and the second voltage divider resistor Rb2, and this divided voltage Vs is input to the inverting input terminal of the operational amplifier CP. The non-inverting input terminal of the operational amplifier CP is connected to the second power supply PS2 via the second resistor R2.

[0077] A connection path LB, which connects the non-inverting input terminal of the operational amplifier CP and the second resistor R2, and the source of the first switch Q1 are connected by a Zener diode DT and a changeover switch SWK. The cathode of the Zener diode DT is connected to the connection path LB, and the anode of the Zener diode DT is connected to the source (low-voltage side terminal) of the first switch Q1. The changeover switch SWK is an N-channel MOSFET, and the drain of the changeover switch SWK is connected to the connection path LB. The source of the changeover switch SWK is connected to the source of the first switch Q1.

[0078] The output terminal of the operational amplifier CP is connected to the source of the first switch Q1 via a series connection of a third resistor R3 and a fourth resistor R4, and the inverting input terminal and the output terminal are connected by a series connection of a fifth resistor R5 and a capacitor CN.

[0079] The adjustment switch SWN is an NPN bipolar transistor, and the collector of the adjustment switch SWN is connected to the cathode of the diode DI. The anode of the diode DI is connected to the charge / discharge path LA. The emitter of the adjustment switch SWN is connected to the source of the first switch Q1. The base of the adjustment switch SWN is connected to the connection point of the third resistor R3 and the fourth resistor R4. The adjustment switch SWN is driven by an output signal ST output from the output terminal of the operational amplifier CP. When the adjustment switch SWN is turned on, charge is discharged from the gate of the first switch Q1 via the charge / discharge path LA.

[0080] The operational amplifier CP is connected to the third power supply PS3 and the source of the first switch Q1, and the range of the output signal ST is determined by the output voltage and source potential of the third power supply PS3. The control unit 70 switches the selector switch SWK to the ON state in normal mode. In this case, the ground voltage, which is the source voltage of the first switch Q1, is applied to the non-inverting input terminal of the operational amplifier CP. In this case, the operational amplifier CP outputs an output signal ST that turns the adjustment switch SWN to the OFF state. This turns the adjustment switch SWN to the OFF state. As a result, the gate voltage Von when the first switch Q1 is turned on becomes the first ON voltage Vα.

[0081] On the other hand, the selector switch SWK is switched to the off state in the heat generation mode. In this case, a target value Vds* is applied to the non-inverting input terminal of the operational amplifier CP. Here, the target value Vds* is the breakdown voltage of the Zener diode DT. The target value Vds* is set to a divided voltage Vs corresponding to the range of the main terminal voltage Vds that changes with changes in the gate voltage Vg in the characteristic that shows the relationship between the gate voltage Vg of the first switch Q1 and the main terminal voltage Vds of the first switch Q1.

[0082] With the configuration described above, when the first switch Q1 is turned on, the adjustment switch SWN is driven to feedback-control the detected divided voltage Vs to the target value Vds*. As a result, when the first switch Q1 is turned on, the gate voltage Von becomes the second on-voltage Vβ, which is lower than the first on-voltage Vα.

[0083] The voltage range of the main terminal voltage Vds corresponding to the range of the gate voltage Vg appropriate for increasing the unit heat quantity HE generated in the switch unit 21 is generally wider than the range of the gate voltage Vg. For this reason, the on-resistance of the switch unit 21 can be adjusted with higher precision by controlling the main terminal voltage Vds to a target value of the main terminal voltage Vds appropriate for increasing the unit heat quantity HE than by controlling the actual gate voltage Vg to a target value of the gate voltage appropriate for increasing the unit heat quantity HE.

[0084] In view of this, in this embodiment, if it is determined that there is a request to increase the unit heat quantity HE generated by the switch unit 21, the selector switch SWK is turned off when the first to fourth switches Q1 to Q4 are turned on in the second switching control. In this case, the divided voltage Vs detected by the operational amplifier CP is feedback-controlled to the target value Vds*. This allows the unit heat quantity HE generated by the first to fourth switches Q1 to Q4 to be increased appropriately.

[0085] <Modification of the first embodiment> The second switching control is not limited to control that reduces the gate voltage Von when the first to fourth switches Q1 to Q4 are turned on compared to when the first switching control is executed. The second switching control may also be control that shortens the switching period Tsw of the first to eighth switches Q1 to Q8 compared to when the first switching control is executed. In this case, the second switching control increases the number of switching operations per unit time compared to when the first switching control is executed, and the switching loss of the first to eighth switches Q1 to Q8 increases. This makes it possible to make the amount of heat generated per unit HE in the first to eighth switches Q1 to Q8 greater than the amount of heat generated per unit HE in the first to eighth switches Q1 to Q8 when the first switching control is executed.

[0086] The second switching control may be a control that reduces the switching speed of the first to eighth switches Q1 to Q8 compared to when the first switching control is executed. Specifically, the resistance of the charging resistor RC shown in FIG. 8 is variable, and when the switches Q1 to Q8 are turned on, the resistance of the charging resistor RC is set to be higher than when the first switching control is executed. This reduces the rate at which charges flow into the gates of the switches Q1 to Q8, thereby slowing down the turn-on speed. Furthermore, when the switches Q1 to Q8 are turned off, the resistance of the discharging resistor RD is set to be higher than when the first switching control is executed. This reduces the rate at which charges flow out of the gates of the switches Q1 to Q8, thereby slowing down the turn-off speed.

[0087] In this case, the second switching control causes larger switching losses in the first to eighth switches Q1 to Q8 than when the first switching control is executed, which makes it possible to make the amount of heat generated per unit HE in the first to eighth switches Q1 to Q8 larger than the amount of heat generated per unit HE in the first to eighth switches Q1 to Q8 when the first switching control is executed.

[0088] Second Embodiment The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the first embodiment, the first and second periods TW1 and TW2 were fixed periods, but this is changed in the second embodiment. In this embodiment, the ratio RT (=TW2 / TW1) of the second period TW2 to the first period TW1 is controlled.

[0089] 9 shows a control block diagram performed by the control unit 70 in the heat generation mode of this embodiment. The control unit 70 includes a first controller 82, a second controller 83, and a third controller 84. In this embodiment, the heat generation controller 81 will be referred to as the first heat generation controller, and the map of the first heat generation controller 81 will be referred to as the first phase map MP1.

[0090] The third controller 84 includes a target heat quantity setting unit 85 and a second heat generation controller 86. The target heat quantity setting unit 85 stores a second phase map MP2. The second phase map MP2 is correlation information that associates the environmental temperature T with the target unit heat quantity HE*. For example, the target unit heat quantity HE* is set to increase as the environmental temperature T decreases. The target heat quantity setting unit 85, which serves as a temperature acquisition unit, sets the target unit heat quantity HE* based on the environmental temperature T detected by the temperature sensor 64.

[0091] The target heat quantity setting unit 85 may adjust the target unit heat quantity HE* based on the temperature of each of the switches Q1 to Q8. Specifically, when the temperature of each of the switches Q1 to Q8 is higher than the target temperature, the target unit heat quantity HE* may be adjusted to decrease the target unit heat quantity HE*, and when the temperature of each of the switches Q1 to Q8 is lower than the target temperature, the target unit heat quantity HE* may be adjusted to increase the target unit heat quantity HE*. This makes it possible to achieve both heat generation in the switch unit 21 and overheat protection for each of the switches Q1 to Q8.

[0092] The second heat generation controller 86 includes a heat quantity deviation calculation unit 87, a second feedback control unit 88, and a third limiter 89. The heat quantity deviation calculation unit 87 calculates a heat quantity deviation ΔHE by subtracting the average unit heat quantity HEave from the target unit heat quantity HE* set by the target heat quantity setting unit 85. The average unit heat quantity HEave is calculated by an average heat quantity calculation unit 87a. The average heat quantity calculation unit 87a calculates the average unit heat quantity HEave based on, for example, the first current I1 and the second current I2. In this embodiment, the heat quantity deviation calculation unit 87 corresponds to the "average heat parameter acquisition unit."

[0093] The second feedback control unit 88 calculates the ratio RT (=TW2 / TW1) as the manipulated variable for feeding back the calculated heat quantity deviation ΔHE to 0. In this embodiment, proportional-integral control using a positive feedback gain is executed as this feedback control. Note that by making the responsiveness of the feedback control executed by the second feedback control unit 88 slower than the responsiveness of the feedback control executed by the first feedback control unit 77 (for example, about 1 / 10), it is possible to suppress interference between these feedback control units.

[0094] The ratio RT calculated by the second feedback control unit 88 is limited to an upper or lower limit by a third limiter 89. The third limiter 89 is set so that the upper limit of the ratio RT decreases as the ambient temperature T increases. The gate voltage driving units 80 in the first controller 82 and the second controller 83 set the first and second periods TW1, TW2 based on the ratio RT output from the third controller 84.

[0095] The second feedback control unit 88 sets the ratio RT so as to feed back the calorie deviation ΔHE to 0, i.e., so that the calculated average unit calorie HEave follows the target unit calorie HE*. As a result, when the calculated average unit calorie HEave is below the target unit calorie HE*, the ratio RT is increased. On the other hand, when the calculated average unit calorie HEave exceeds the target unit calorie HE*, the ratio RT is decreased.

[0096] Figure 10 shows the transition of the transmitted power value PW and the unit heat quantity HE in the heat generation mode of this embodiment. In the example shown in Figure 10, by controlling the ratio RT of the second period TW2 to the first period TW1 to be greater than 1, the average unit heat quantity HEave can be made closer to the target unit heat quantity HE*.

[0097] FIG. 11 shows the average power value PWave and the average unit heat energy HEave in the heat generation mode. FIG. 11 shows the average power value PWave and the average unit heat energy HEave in each of the following cases: (1) when the target average power value PWave* is equal to the target unit heat energy HE*, (2) when the target average power value PWave* is greater than the target unit heat energy HE*, and (3) when the target average power value PWave* is smaller than the target unit heat energy HE*. FIG. 11(A) shows the average power value PWave and the average unit heat energy HEave of a comparative example. The comparative example is a control in which only the second switching control is executed out of the first and second switching controls. In the comparative example shown in FIG. 11(A), in all cases, the average unit heat energy HEave can be controlled to the target unit heat energy HE*, but the average power value PWave cannot be controlled to the target average power value PWave*. On the other hand, in the present embodiment shown in FIG. 11(B), in either case, the average unit heat quantity HEave can be controlled to the target unit heat quantity HE*, and the average power value PWave can be brought closer to the target average power value PWave*.

[0098] Third Embodiment The third embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the first embodiment, the first and second periods TW1 and TW2 were longer than one switching period Tsw of the first switch Q1, but this is changed. In this embodiment, the first and second periods TW1 and TW2 are set to be shorter than one switching period Tsw, and the first and second periods TW1 and TW2 are set within the on period Ton during which the first switch Q1 is in the on state within one switching period Tsw of the first switch Q1.

[0099] FIG. 12 shows a block diagram of control executed by the control unit 70 in the heat generation mode of this embodiment. The control unit 70 includes a first controller 82 and a third controller 84. In the first controller 82, the value input to the current calculation unit 72 of the first controller 82 shown in FIG. 3 is changed from the target average power value PWave* to the target power value PW*, and the value input to the current deviation calculation unit 76 of the current controller 75 serving as the power calculation unit is changed from the average current Iave2 to the second current I2. In addition, in the third controller 84, the value input to the heat quantity deviation calculation unit 87 of the third controller 84 shown in FIG. 9 is changed from the average unit heat quantity HEave to the unit heat quantity HE. The gate voltage driver 80 of the first controller 82 sets first and second periods TW1 and TW2 within the on-period Ton during which the first switch Q1 is in the on-state, based on the ratio RT (=TW2 / TW1) output from the third limiter 89. In this embodiment, the heat quantity deviation calculation unit 87 corresponds to the "heat parameter acquisition unit."

[0100] The first feedback control unit 77 sets the inter-port phase φ21 so as to feedback the current deviation ΔI2 to zero, that is, so that the detected second current I2 follows the command current Iref2. The detected second current I2 correlates with the transmitted power value PW, and the command current Iref2 correlates with the target power value PW*. Therefore, by calculating the length of the inter-port phase φ21 in the first switching control so that the detected second current I2 follows the command current Iref2, the transmitted power value PW can be brought closer to the target power value PW*.

[0101] Furthermore, the second feedback control unit 88 sets the ratio RT so as to feedback the heat quantity deviation ΔHE to 0, i.e., so that the unit heat quantity HE generated by the switch unit 21 follows the target unit heat quantity HE*. As a result, when the calculated unit heat quantity HE is lower than the target unit heat quantity HE*, the ratio RT is increased. On the other hand, when the calculated unit heat quantity HE exceeds the target unit heat quantity HE*, the ratio RT is decreased. As a result, the unit heat quantity HE generated by the switch unit 21 can be brought closer to the target unit heat quantity HE*.

[0102] Fig. 13 shows transitions in the drive states of the first and fifth switches Q1 and Q5 in the heat generation mode. Fig. 13 shows transitions in the drive states of the first and fifth switches Q1 and Q5 in a first state in which the target unit heat quantity HE* is set to the first unit heat quantity HE1 and the target power value PW* is set to the first power value PW1, and in a second state in which the target unit heat quantity HE* is set to a second unit heat quantity HE2 that is larger than the first unit heat quantity HE1 and the target power value PW* is set to the first power value PW1. In Fig. 13, (B) and (D) show transitions in the gate voltages Vg of the first and fifth switches Q1 and Q5, (E) shows transitions in the first current I1 flowing through the first high potential side terminal CH1 and the first coil 50a, and (F) shows transitions in the conduction loss of the first switch Q1.

[0103] 13A to 13D, in the heat generation mode of this embodiment, first and second periods TW1 and TW2 are set within the on-period Ton of one switching cycle Tsw. In this embodiment, the first period TW1 includes a reverse polarity period in which the first switch Q1 is in the on-state and the fifth switch Q5 is in the off-state.

[0104] As shown in Figure 13(E), during the first period TW1, a first current I1 with a current amplitude IH flows. The longer the inter-port phase φ21, the larger the current amplitude IH. Furthermore, the larger the current amplitude IH, the larger the transmitted power value PW during the on period Ton. During the second period TW2, the first current I1 decreases to zero at a constant rate. As shown in Figure 13(F), during the period in which the first current I1 decreases during the second period TW2, the conduction loss in the first switch Q1 increases, and unit heat HE is generated in the first switch Q1.

[0105] The unit heat quantity HE of the first switch Q1 increases as the second period TW2 in the on-period Ton of one switching cycle Tsw increases. Therefore, for example, when switching from a first state in which the target unit heat quantity HE* is relatively low to a second state in which the target unit heat quantity HE* is relatively high, the ratio RT is increased compared to the first state to increase the unit heat quantity HE. On the other hand, increasing the ratio RT reduces the transmitted power value PW of the first switch Q1. Therefore, in this embodiment, when switching from the first state to the second state, the ratio RT is increased and the inter-port phase φ21 is lengthened compared to the first state. This allows the unit heat quantity HE to be increased while maintaining the transmitted power value PW. According to the embodiment described above, the transmitted power value PW can be brought closer to the target power value PW*, while the unit heat quantity HE generated by the switch unit 21 can be brought closer to the target unit heat quantity HE*.

[0106] <Fourth embodiment> The fourth embodiment will be described below with reference to the drawings, focusing on the differences from the third embodiment. In the third embodiment, the first period TW1 includes a reverse polarity period, but this is changed in the present embodiment. In the second period TW2, a reverse polarity period is included, and the second switching control is executed during the reverse polarity period.

[0107] 14 shows the current paths of the first current I1 and the second current I2 during the reverse polarity period. In the first full-bridge circuit 30, a current path is formed that includes the first high-potential side terminal CH1, the first switch Q1, the first coil 50a, the fourth switch Q4, and the first low-potential side terminal CL1. Meanwhile, in the second full-bridge circuit 40, a current path is formed that includes the second high-potential side terminal CH2, the seventh switch Q7, the second coil 50b, the eighth switch Q8, and the second low-potential side terminal CL2. In this case, in the second switching control, the conduction loss can be increased not only for the first and fourth switches Q1 and Q4 of the first full-bridge circuit 30 but also for the seventh and eighth switches Q7 and Q8 of the second full-bridge circuit 40 by setting the gate voltage Von when the first and fourth switches Q1 and Q4 and the seventh and eighth switches Q7 and Q8 are turned on to the second on-voltage Vβ. In other words, by performing the second switching control during the reverse polarity period, the unit heat quantity HE generated in the switch section 21 can be increased compared to when the first switching control is performed during the inter-port phase φ21.

[0108] During the reverse polarity period, the polarity of the first voltage V1 applied from the first full-bridge circuit 30 to the first coil 50a is opposite to the polarity of the second voltage V2 applied from the second full-bridge circuit 40 to the second coil 50b. Therefore, the voltage applied to the transformer 50 is higher than during periods other than the reverse polarity period in the on-period Ton, and the first and second currents I1 and I2 change more rapidly. As a result, the first current sensor 60, the first voltage sensor 61, the second current sensor 62, and the second voltage sensor 63 require higher responsiveness, which increases costs. Therefore, in order to reduce costs, the third embodiment, in which the second switching control is executed during periods other than the reverse polarity period, offers significant advantages.

[0109] Fifth Embodiment The fifth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the first embodiment, the first and second switching controls are executed in the heat generation mode, but this is changed. In this embodiment, only the second switching control is executed in the heat generation mode.

[0110] FIG. 15 shows a block diagram of control executed by the control unit 70 in the heat generation mode of this embodiment. The control unit 70 includes a first controller 82 and a third controller 84. In the first controller 82, the value input to the current calculation unit 72 of the first controller 82 shown in FIG. 3 is changed from the target average power value PWave* to the target power value PW*, and the value input to the current deviation calculation unit 76 is changed from the average current Iave2 to the second current I2. In the third controller 84, the value input to the heat quantity deviation calculation unit 87 of the third controller 84 shown in FIG. 9 is changed from the average unit heat quantity HEave to the unit heat quantity HE. In addition, the second heat generation control unit 86 includes a third feedback control unit 90 and a fourth limiter 91 instead of the second feedback control unit 88 and the third limiter 89 shown in FIG. 12.

[0111] The third feedback control unit 90 calculates a target value Vds* as a manipulated variable for feeding back the heat quantity deviation ΔHE calculated by the heat quantity deviation calculation unit 87 to 0. In this embodiment, proportional-integral control is executed as this feedback control. Note that the feedback control executed by the third feedback control unit 90 is not limited to proportional-integral control, and may be, for example, proportional-integral-derivative control.

[0112] The target value Vds* calculated by the third feedback control unit 90 is limited to an upper limit or a lower limit by a fourth limiter 91. The gate voltage driving unit 80 of the first controller 82 sets the second on-voltage Vβ as a specified voltage based on the target value Vds* output from the third controller 84.

[0113] The third feedback control unit 90 sets the target value Vds* so as to feedback the heat quantity deviation ΔHE to 0, that is, so that the unit heat quantity HE generated by the switch unit 21 follows the target unit heat quantity HE*. As a result, when the unit heat quantity HE generated by the switch unit 21 is lower than the target unit heat quantity HE*, the target value Vds* is increased. On the other hand, when the calculated unit heat quantity HE exceeds the target unit heat quantity HE*, the target value Vds* is decreased.

[0114] The gate voltage driver 80 sets the second on-voltage Vβ higher as the target value Vds* is lower. Furthermore, the higher the second on-voltage Vβ is set, the more the unit heat quantity HE generated by the switch unit 21 increases. Therefore, by setting the target value Vds* so that the unit heat quantity HE generated by the switch unit 21 follows the target unit heat quantity HE*, the unit heat quantity HE generated by the switch unit 21 can be made to approach the target unit heat quantity HE*.

[0115] Fig. 16 shows the transition of the drive states of the first and fifth switches Q1 and Q5 in the heat generation mode. Fig. 16 shows the transition of the drive states of the first and fifth switches Q1 and Q5 in the first and second states described in Fig. 13. Figs. 16(A) to (E) correspond to Figs. 13(A), (C), and (D) to (F).

[0116] As shown in FIGS. 16A and 16B, in the heat generation mode of this embodiment, the on-period Ton of one switching cycle Tsw becomes the second period TW2, and the inter-port phase φ21 is included in the second period TW2.

[0117] As shown in FIG. 16(C), during the on-period Ton, the current amplitude IH increases as the inter-port phase φ21 increases. The larger the current amplitude IH, the larger the transmitted power value PW during the on-period Ton. After the inter-port phase φ21 elapses, the first current I1 decreases. As shown in FIG. 16(E), during the period in which the first current I1 decreases, a conduction loss occurs in the first switch Q1, and a unit heat quantity HE is generated in the first switch Q1.

[0118] The unit heat quantity HE of the first switch Q1 increases as the target value Vds* in the on-period Ton of one switching cycle Tsw increases. Therefore, for example, when switching from a first state in which the target unit heat quantity HE* is relatively low to a second state in which the target unit heat quantity HE* is relatively high, the target value Vds* is made larger than that in the first state, as shown in FIG. 16(D). Specifically, for example, in the configuration shown in FIG. 8, the Zener diode DT may be omitted and the power supply voltage of the second power supply PS2 may be made variable. When switching to the second state, the power supply voltage of the second power supply PS2 is set higher than that in the first state. As a result, the second on-voltage Vβ is made lower than that in the first state.

[0119] On the other hand, when the second on-state voltage Vβ is reduced, the transmitted power value PW of the first switch Q1 decreases. Therefore, in this embodiment, when switching from the first state to the second state, the second on-state voltage Vβ is made lower than in the first state, and the inter-port phase φ21 is made longer than in the first state. This makes it possible to increase the unit heat quantity HE while maintaining the transmitted power value PW.

[0120] Sixth Embodiment The sixth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the first embodiment, a full-bridge circuit is used in the configuration of the power conversion device 20. In this embodiment, the configuration of the power conversion device 20 is changed to a phase-shift full-bridge circuit.

[0121] A configuration diagram of this embodiment is shown in Fig. 17. In Fig. 17, the same components as those shown in Fig. 1 are denoted by the same reference numerals for convenience. In this embodiment, the switch section 21 includes a full-bridge circuit 30, a first diode DI1, a second diode DI2, a reactor 101, and a transformer 50, and the transformer 50 has first to third coils 50a to 50c.

[0122] A first end of the second coil 50b is connected to the anode of the first diode DI1, and a second end of the second coil 50b is connected to the second low potential side terminal CL2. A first end of the third coil 50c is connected to the second low potential side terminal CL2, and a second end of the third coil 50c is connected to the anode of the second diode DI2. A first end of the reactor 101 is connected to the cathodes of the first and second diodes DI1 and DI2, and a second end of the reactor 101 is connected to the second high potential side terminal CH2.

[0123] The first coil 50a and the third coil 50c are magnetically coupled to each other. When the potential of the first end of the first coil 50a becomes higher relative to the second end, an induced voltage is generated in the third coil 50c such that the potential of the second end is higher than the first end. On the other hand, when the potential of the second end of the first coil 50a becomes higher relative to the first end, an induced voltage is generated in the third coil 50c such that the potential of the second end is lower than the first end.

[0124] The control unit 70 outputs a gate voltage Vg to the gates of the first to fourth switches Q1 to Q4 and turns on and off the first to fourth switches Q1 to Q4 based on the detected values I1, V1, I2, V2, and T. In this embodiment, the first current I1 is positive when a current flows from the first low potential side terminal CL1 to the storage battery 10, and negative when a current flows in the opposite direction.

[0125] In the present embodiment described above in detail, the transmitted power value PW can also be controlled by the phase difference between the first and second switches Q1, Q2 and the third and fourth switches Q3, Q4. Furthermore, within the on-period Ton of each switch Q1 to Q4, a first period TW1 in which the gate voltage Von is set to a first on-voltage Vα and a second period TW2 in which the gate voltage Von is set to a second on-voltage Vβ are provided, and the unit heat quantity HE can be controlled by controlling the ratio RT (=TW2 / TW1).

[0126] Seventh Embodiment The seventh embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the first embodiment, a full-bridge circuit is used as the configuration of the power conversion device 20, but this is changed. In this embodiment, the configuration of the power conversion device 20 is a step-up chopper circuit. Note that the configuration of the power conversion device 20 may also be a step-down chopper circuit or a step-up / step-down chopper circuit.

[0127] A configuration diagram of this embodiment is shown in Fig. 18. In Fig. 18, the same components as those shown in Fig. 1 are denoted by the same reference numerals for convenience. In this embodiment, the switch unit 21 includes a reactor 102 and a half-bridge circuit 103.

[0128] The half-bridge circuit 103 includes an eleventh switch Q11 and a twelfth switch Q12. In this embodiment, the eleventh and twelfth switches Q11 and Q12 are IGBTs. The collector of the eleventh switch Q11 is connected to the second high potential side terminal CH2. The emitter of the eleventh switch Q11 is connected to the collector of the twelfth switch Q12. The emitter of the twelfth switch Q12 is connected to the first low potential side terminal CL1 and the second low potential side terminal CL2. Freewheeling diodes are connected in anti-parallel to the eleventh and twelfth switches Q11 and Q12.

[0129] A first end of the reactor 102 is connected to the first high potential side terminal CH1, and a second end of the reactor 102 is connected to the emitter of the eleventh switch Q11 and the collector of the twelfth switch Q12.

[0130] The control unit 70 outputs a gate voltage Vg to the gates of the eleventh and twelfth switches Q11 and Q12 based on the detected values I1, V1, I2, V2, and T, and turns the eleventh and twelfth switches Q11 and Q12 on and off. The control unit 70 calculates the duty ratio of the twelfth switch Q12 to feedback control the current flowing through the reactor 102 to a target current.

[0131] In the present embodiment described above in detail, the transmitted power value PW can also be controlled by the duty ratio of the twelfth switch Q12. Furthermore, within the on-period Ton of the twelfth switch Q12, a first period TW1 in which the gate voltage Von of the twelfth switch Q12 is set to a first on-voltage Vα and a second period TW2 in which the gate voltage Von is set to a second on-voltage Vβ are provided, and the unit heat quantity HE can be controlled by controlling the ratio RT (=TW2 / TW1).

[0132] Eighth Embodiment The sixth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the first embodiment, a full-bridge circuit is used in the configuration of the power conversion device 20. In this embodiment, the configuration of the power conversion device 20 is changed to a three-phase inverter circuit.

[0133] A configuration diagram of this embodiment is shown in Figure 19. In Figure 19, the same components as those previously shown in Figure 1 are denoted by the same reference numerals for convenience. In this embodiment, the power conversion system includes a storage battery 10, a rotating electric machine 120 as a power supply target, a high potential side terminal CH, a low potential side terminal CL, a U-phase terminal CNU, a V-phase terminal CNV, a W-phase terminal CNW, and a power conversion device 20, and the power conversion device 20 includes an inverter 104 as a switch unit.

[0134] The rotating electric machine 120 is a brushless synchronous machine, such as a permanent magnet synchronous machine, and includes U-, V-, and W-phase windings 121U, 121V, and 121W, which are three-phase armature windings.

[0135] The rotating electric machine 120 is connected to the storage battery 10 via an inverter 104. The inverter 104 includes a series connection of upper-arm switches QUH, QVH, and QWH and lower-arm switches QUL, QVL, and QWL. A first end of a U-phase winding 121U is connected to the connection point of the U-phase upper and lower-arm switches QUH and QUL via a U-phase terminal CNU. A first end of a V-phase winding 121V is connected to the connection point of the V-phase upper and lower-arm switches QVH and QVL via a V-phase terminal CNV. A first end of a W-phase winding 121W is connected to the connection point of the W-phase upper and lower-arm switches QWH and QWL via a W-phase terminal CNW. Second ends of the U-, V-, and W-phase windings 121U, 121V, and 121W are connected at a neutral point PT.

[0136] In this embodiment, an IGBT is used as each of the switches QUH to QWL, and a freewheel diode is connected in antiparallel to each of the switches QUH to QWL.

[0137] The inverter 104 is provided with a capacitor 105 on the storage battery 10 side of each of the switches QUH to QWL. A high potential side terminal of the capacitor 105 is connected to a high potential side terminal CH, and a low potential side terminal of the capacitor 105 is connected to a low potential side terminal CL. The capacitor 105 may be provided outside the inverter 104.

[0138] The power conversion device 20 includes a current sensor 106. The current sensor 106 detects currents of at least two phases out of the phase currents IU, IV, and IW flowing through the rotating electric machine 120.

[0139] The control unit 70 outputs a gate voltage Vg to the gate of each of the switches QUH to QWL based on each of the detected values IU, IV, IW, and T, and turns each of the switches QUH to QWL on and off. The control unit 70 controls the modulation rate of each of the switches SUH to SWL in order to feedback control the control amount of the rotating electric machine 120 to a command value. In this embodiment, the control amount is torque.

[0140] In the present embodiment described above in detail, the transmitted power value PW can also be controlled by the modulation factor of each of the switches SUH to SWL. Furthermore, within the on-period Ton of each of the switches SUH to SWL, a first period TW1 in which the gate voltage Von is set to a first on-voltage Vα and a second period TW2 in which the gate voltage Von is set to a second on-voltage Vβ are provided, and the unit heat quantity HE can be controlled by controlling the ratio RT (=TW2 / TW1).

[0141] Ninth Embodiment The ninth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In the ninth embodiment, a heat transfer section 110 is added to the configuration of the first embodiment.

[0142] FIG. 20 shows a configuration diagram of this embodiment. In FIG. 20, the same components as those shown in FIG. 1 are denoted by the same reference numerals for convenience. The power conversion device 20 includes a heat transfer unit 110. In this embodiment, the heat transfer unit 110 is configured to absorb heat generated by the heat exchange target elements, which are the switches Q1 to Q8, the transformer 50, and the power supply target 11. The heat transfer unit 110 transfers the absorbed heat to the temperature increase target element, thereby increasing the temperature of the temperature increase target element. The temperature increase target element is, for example, the power supply target 11.

[0143] The heat transfer unit 110 may be, for example, a unit that includes a circulation path through which cooling water circulates between the heat exchange target element and the temperature increase target element, and that increases the temperature of the temperature increase target element via this cooling water. The heat transfer unit 110 may also be, for example, a unit that uses gas (air) as a cooling fluid. The heat transfer unit 110 may also be, for example, a component such as a heat sink that does not use a cooling fluid and is in contact with the heat exchange target element and the temperature increase target element.

[0144] This allows the heat generated during power conversion to be recovered and transferred to the element whose temperature is to be increased, thereby efficiently increasing the temperature of the element whose temperature is to be increased.

[0145] <Other embodiments> The above-described embodiments may be modified as follows.

[0146] In the first and second embodiments, the specified period TK is the total period of the first period TW1 and the second period TW2, but the specified period TK may be set to be longer than this total period.

[0147] The switching controls performed in the heat generation modes of the first to fifth embodiments may be performed by combining two or more of these switching controls. For example, the switching controls performed in the heat generation modes of the first and fifth embodiments may be combined to simultaneously control the length of the inter-port phase φ21 in the first switching control and the gate voltage Von when the first to fourth switches Q1 to Q4 are turned on in the second switching control.

[0148] The configuration of the power conversion device 20 is not limited to those shown in the first, fourth, fifth, and sixth embodiments, and may be a forward DC-DC converter, an LLC DC-DC converter, a single-phase DC-AC inverter, or the like.

[0149] In the fourth embodiment, in the second switching control executed during the reverse polarity period, the gate voltage Von when the switches Q1 and Q4 included in the first full-bridge circuit 30 and the switches Q7 and Q8 included in the second full-bridge circuit 40 are turned on is set to the second on-voltage Vβ. However, this is not limiting. The gate voltage Von when only one of the switches Q1 and Q4 included in the first full-bridge circuit 30 and the switches Q7 and Q8 included in the second full-bridge circuit 40 is turned on may be set to the second on-voltage Vβ.

[0150] The thermal parameter is not limited to the unit heat quantity HE, but may be, for example, the temperature of any of the switch unit 21, the heat transfer unit 110, and the temperature-increasing element. The temperature-increasing element is, for example, the power conversion device 20 or the storage battery 10.

[0151] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium. [Explanation of symbols]

[0152] 20...power conversion device, 21...switch unit, 70...control unit, CH1...first high potential side terminal, CH2...second high potential side terminal, CL1...first low potential side terminal, CL2...second low potential side terminal.

Claims

1. A power conversion device (20) having input terminals (CH1, CL1), output terminals (CH2, CL2) and a switch unit (21, 104), which transmits power input from the input terminals to the output terminals by performing switching control of the switch unit, a request determination unit that determines whether or not there is a request to increase the amount of heat generated in the switch unit in response to the execution of the switching control; a control unit (70) that, when it is determined that there is a request for an increase, alternately executes a first switching control for transmitting power from the input terminal to the output terminal and a second switching control in which the amount of heat generated in the switch unit is greater than the amount of heat generated in the switch unit due to execution of the first switching control; Equipped with The control unit The first switching control is performed in a first period (TW1) longer than one switching period (Tsw) of the switch unit, and the second switching control is performed in a second period (TW2) longer than one switching period of the switch unit, a power conversion device that performs the first switching control to control an average power value (PWave), which is a time average value of a transmitted power value (PW) from the input terminal to the output terminal during a specified period (TK) that is equal to or greater than the sum of the first period and the second period, to a target average power value (PWave*).

2. an average thermal parameter acquisition unit that acquires an average thermal parameter (HEave) that is a time average value of the heat amount (HE) generated in the switch unit during the specified period in association with execution of the first switching control and the second switching control, when the heat amount (HE) or a correlation value thereof is set as a thermal parameter; The control unit If the acquired thermal parameter is below a target value (HE*), increasing the ratio (RT) of the second period to the first period; The power conversion device of claim 1 , wherein the ratio is reduced when the acquired thermal parameter exceeds the target value.

3. 3. The power conversion device according to claim 1, wherein the control unit executes, as the second switching control, at least one of control to reduce a gate voltage (Von) of the switch unit compared to when the first switching control is executed, control to shorten one switching period of the switch unit compared to when the first switching control is executed, and control to reduce a switching speed of the switch unit compared to when the first switching control is executed.

4. the control unit executes, as the second switching control, control to lower a gate voltage of the switch unit compared to when the first switching control is executed; a voltage detection unit (Rb1, Rb2) that detects a voltage (Vds) between the main terminals of the switch unit; the control unit operates a gate voltage of the switch unit so as to feedback-control the detected voltage between the main terminals to a target value (Vds*) in the second switching control; The power conversion device according to claim 1 , wherein the target value is set within a range of the voltage between the main terminals that changes in accordance with a change in the gate voltage.

5. The switch unit a transformer (50) having a first coil (50a) and a second coil (50b) that are magnetically coupled to each other; an input-side full-bridge circuit (30) having input-side switches (Q1 to Q4), connected to the input-side terminals and the first coil, and converting a DC voltage input from the input-side terminals into an AC voltage and applying the AC voltage to the first coil by executing switching control of the input-side switches; an output-side full-bridge circuit (40) having output-side switches (Q5 to Q8), connected to the output-side terminals and the second coil, and converting an AC voltage output from the second coil into a DC voltage by executing switching control of the output-side switches, and outputting the DC voltage to the output-side terminals; When a period in which the polarity of the voltage applied from the input side full bridge circuit to the first coil and the polarity of the voltage applied from the output side full bridge circuit to the second coil are opposite to each other is defined as an opposite polarity period, the control unit: When the transmission power value falls below the target average power value in the second period, the first switching control is executed to extend the length of the reverse polarity period included in the first period; 5. The power conversion device according to claim 1, wherein when the transmission power value exceeds the target average power value in the second period, the first switching control is performed to shorten the length of the reverse polarity period included in the first period.

6. A power conversion device (20) having input terminals (CH1, CL1), output terminals (CH2, CL2) and a switch unit (21, 104), which transmits power input from the input terminals to the output terminals by performing switching control of the switch unit, a request determination unit that determines whether or not there is a request to increase the amount of heat generated in the switch unit in response to the execution of the switching control; a control unit that, when it is determined that there is a request for an increase, executes a first switching control of setting a gate voltage (Von) of the switch unit to a first voltage during a period (Ton) in which the switch unit is turned on in one switching cycle of the switch unit, and a second switching control of setting the gate voltage of the switch unit to a second voltage lower than the first voltage; a thermal parameter acquisition unit that acquires a heat quantity (HE) generated in association with execution of the first switching control and the second switching control or a thermal parameter that is a correlation value thereof; Equipped with The control unit When the acquired thermal parameter is lower than a target value (HE*), increasing a ratio (TW2 / TW1) of an execution period (TW2) of the second switching control to an execution period (TW1) of the first switching control; The power converter reduces the ratio if the acquired thermal parameter exceeds the target value.

7. The switch unit a transformer (50) having a first coil (50a) and a second coil (50b) that are magnetically coupled to each other; an input-side full-bridge circuit (30) having input-side switches (Q1 to Q4), connected to the input-side terminals and the first coil, and converting a DC voltage input from the input-side terminals into an AC voltage and applying the AC voltage to the first coil by executing switching control of the input-side switches; an output-side full-bridge circuit (40) having output-side switches (Q5 to Q8), connected to the output-side terminals and the second coil, and converting an AC voltage output from the second coil into a DC voltage by executing switching control of the output-side switches, and outputting the DC voltage to the output-side terminals; a power calculation unit that calculates a value of power (PW) transmitted from the input terminal to the output terminal during a period in which the switch unit is turned on; The control unit defines a period in which the polarity of the voltage applied from the input side full bridge circuit to the first coil and the polarity of the voltage applied from the output side full bridge circuit to the second coil are opposite to each other as a reverse polarity period (φ21). When the calculated transmission power value is lower than a target power value (PW*), switching control is performed on the input side switch and the output side switch so as to extend the length of the reverse polarity period; The power conversion device according to claim 6 , wherein, when the calculated transmission power value exceeds the target power value, switching of the input-side switch and the output-side switch is controlled so as to shorten the length of the reverse polarity period.

8. the reverse polarity period includes a period during which the second switching control is performed, The power conversion device according to claim 7 , wherein the control unit sets a gate voltage of at least one of the input-side switch and the output-side switch to the second voltage during an execution period of the second switching control included in the reverse polarity period.

9. 8. The power conversion device according to claim 7, wherein the control unit performs the second switching control during a period other than the reverse polarity period in which the switch unit is turned on, and sets a gate voltage of the input-side switch to the second voltage in the second switching control.

10. a voltage detection unit (Rb1, Rb2) that detects a voltage (Vds) between the main terminals of the switch unit; the control unit operates a gate voltage of the switch unit so as to feedback-control the detected voltage between the main terminals to a target value (Vds*) in the second switching control; The power conversion device according to claim 6 , wherein the target value is set within a range of the voltage between the main terminals that changes in accordance with a change in the gate voltage.

11. The power conversion device according to claim 1 , further comprising a heat transfer section (110) that absorbs heat generated in the switch section and transfers the absorbed heat to an element whose temperature is to be increased.

12. a temperature acquisition unit that acquires a temperature (T) of at least one of the switch unit and the heat transfer unit, 12. The power conversion device according to claim 11, wherein, when it is determined that there is an increase request, the control unit performs switching control of the switch unit such that the higher the acquired temperature, the lower the upper limit value of the amount of heat generated by the switch unit.

13. A program for a power conversion device (20) having input terminals (CH1, CL1), output terminals (CH2, CL2) and a switch unit (21, 104), which transmits power input from the input terminals to the output terminals by controlling switching of the switch unit, On the computer, a request determination process for determining whether or not there is a request to increase the amount of heat generated in the switch unit in response to the execution of the switching control; a control process for alternately executing, when it is determined that there is a request for an increase, a first switching control for transmitting power from the input terminal to the output terminal and a second switching control in which the amount of heat generated by the switch unit is greater than the amount of heat generated by the switch unit due to the execution of the first switching control; Execute In the control process, The first switching control is performed in a first period (TW1) longer than one switching period (Tsw) of the switch unit, and the second switching control is performed in a second period (TW2) longer than one switching period of the switch unit, a program that executes the first switching control to control an average power value (PWave), which is a time average value of a transmitted power value (PW) from the input terminal to the output terminal, to a target average power value (PWave*) during a specified period (TK) that is equal to or greater than the total period of the first period and the second period.

14. A program for a power conversion device (20) having input terminals (CH1, CL1), output terminals (CH2, CL2) and a switch unit (21, 104), which transmits power input from the input terminals to the output terminals by controlling switching of the switch unit, On the computer, a request determination process for determining whether or not there is a request to increase the amount of heat generated in the switch unit in response to the execution of the switching control; a control process that executes, when it is determined that there is a request for an increase, a first switching control that sets a gate voltage (Von) of the switch unit to a first voltage and a second switching control that sets the gate voltage of the switch unit to a second voltage lower than the first voltage during a period (Ton) in which the switch unit is turned on in one switching cycle of the switch unit; a thermal parameter acquisition process for acquiring a heat quantity (HE) generated in association with execution of the first switching control and the second switching control or a thermal parameter that is a correlation value thereof; Execute In the control process, When the acquired thermal parameter is lower than a target value (HE*), increasing a ratio (TW2 / TW1) of an execution period (TW2) of the second switching control to an execution period (TW1) of the first switching control; If the acquired thermal parameter exceeds the target value, the program decreases the ratio.

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