Power conversion device, program

Abstract

To provide an electric power conversion device capable of appropriately increasing a heating amount of a switching part in the case where there is a request of increase of the heating amount generated in the switching part in accordance with execution of switching control.SOLUTION: An electric power conversion device performs control that deteriorates a gate voltage of a first switch Q1 rather than it is determined that no request for increasing exists in the case where it is determined that the request for increasing a heat amount generated in the first switch Q1 exists. The electric power conversion device comprises partial pressure resistors Rb1 and Rb2 that detect a main inter-terminal voltage of the first switch Q1. The electric power conversion device operates the gate voltage of the first switch Q1 so as to perform feedback control of the main inter-terminal voltage Vs detected to a target value Vs* when the first switch Q1 is turned on in the case where it is determined that a request for increasing exists. The target value Vs* is set within a range of the main inter-terminal voltage of the first switch Q1 that is changed in accordance with the change of the gate voltage of the first switch Q1.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power conversion device and program and pertains thereto.

Background Art

[0002] Conventionally, by switching control of a switch section included in a power conversion device, electrical energy input from a power storage section is converted into thermal energy, and the power storage section is heated with that thermal energy. Patent Document 1 discloses a power conversion device that reduces the gate voltage when the switch section is in the on state and increases the on-resistance of the switch section. By increasing the on-resistance, the conduction loss of the switch section increases, and the amount of heat generated in the switch section can be increased. The generated heat is used to raise the temperature of the power storage section.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An appropriate gate voltage for increasing the amount of heat is a value within a very narrow voltage range. In this voltage range, the change amount of the on-resistance per unit change amount of the gate voltage is large. Here, the appropriate gate voltage range for increasing the amount of heat depends on the temperature of the switch section, individual differences, etc. For this reason, even when the deviation of the actual gate voltage from the above appropriate gate voltage range is small, there is a concern that the on-resistance may significantly decrease with respect to the assumed value. In this case, there is a concern that the amount of heat generated in the switch section may significantly decrease.

[0005] The present invention has been made in view of the above problems, and its main object is to provide a power conversion device that can appropriately increase the heat amount of a switch unit when there is an increasing demand for the heat amount generated in the switch unit accompanying the execution of switching control of the switch unit. and program To provide the same.

Means for Solving the Problems

[0006] The present invention is a power conversion device having an input-side terminal, an output-side terminal, and a switch unit, and transmitting power input from the input-side terminal to the output-side terminal by performing switching control of the switch unit. A requirement determination unit that determines whether there is an increasing demand for the heat amount generated in the switch unit accompanying the execution of the switching control; A gate control unit that, when it is determined that there is the increasing demand, performs control to lower the gate voltage of the switch unit more than when it is determined that there is no increasing demand; A voltage detection unit that detects the voltage between the main terminals of the switch unit, and is provided with: When it is determined that there is the increasing demand and the switch unit is turned on, the gate control unit operates the gate voltage of the switch unit to perform feedback control of the detected voltage between the main terminals to a target value. The target value is set within a range of the voltage between the main terminals that changes with the change in the gate voltage.

[0007] The voltage range of the voltage between the main terminals corresponding to the appropriate gate voltage range for increasing the heat amount is generally wider than the above gate voltage range. For this reason, rather than controlling the actual gate voltage to the target value of the appropriate gate voltage for increasing the heat amount, controlling the actual voltage between the main terminals to the target value of the appropriate voltage between the main terminals for increasing the heat amount can adjust the on-resistance of the switch unit with high precision.

[0008] In view of this point, in the present invention, when it is determined that there is an increase requirement for the amount of heat generated in the switch section and the switch section is turned on, the gate voltage is operated to feedback-control the main terminal voltage detected by the voltage detection section to a target value. The target value is a range of appropriate main terminal voltages for increasing the amount of heat, and is set within a range of the main terminal voltage that changes as the gate voltage changes. According to the present invention described above, the heat generation amount of the switch section can be appropriately increased.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Modes for Carrying Out the Invention

[0010] <First Embodiment> Hereinafter, a first embodiment in which the power conversion device according to the present invention is embodied will be described with reference to the drawings. The power conversion device of this embodiment is mounted on an electrified vehicle such as a plug-in hybrid vehicle or an electric vehicle.

[0011] 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.

[0012] The storage battery 10 supplies power to the power supply target 11 via the power conversion device 20. The storage battery 10 is a rechargeable secondary battery, for example, a lithium-ion storage battery.

[0013] 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 the present 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.

[0014] The switch unit 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 the present embodiment, the first to eighth switches Q1 to Q8 are N-channel MOSFETs.

[0015] In the first full-bridge circuit 30, the first high-potential side terminal CH1 is connected to the drains of the first switch Q1 and the third switch Q3. The drain of the second switch Q2 is connected to the source of the first switch Q1, and the drain of the fourth switch Q4 is connected to the source of the third switch Q3. The first low-potential side terminal CL1 is connected to the sources of the second switch Q2 and the fourth switch Q4. The positive terminal of the storage battery 10 is connected to the first high-potential side terminal CH1, and the 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 terminal and the negative terminal of the storage battery 10.

[0016] In the second full-bridge circuit 40, a second high-potential side terminal CH2 is connected to the drains of the fifth switch Q5 and the seventh switch Q7. The drain of the sixth switch Q6 is connected to the source of the fifth switch Q5, and the drain of the eighth switch Q8 is connected to the source of the seventh switch Q7. A second low-potential side terminal CL2 is connected to the sources of the sixth switch Q6 and the eighth switch Q8. A power supply target 11 and a second capacitor 13 are connected in parallel between the second high-potential side terminal CH2 and the second low-potential side terminal CL2.

[0017] The transformer 50 has a first coil 50a and a second coil 50b. The source of the first switch Q1 and the drain of the second switch Q2 are connected to the first end of the first coil 50a, and the source of the third switch Q3 and the drain of the fourth switch Q4 are connected to the second end of the first coil 50a. The source of the fifth switch Q5 and the drain of the sixth switch Q6 are connected to the first end of the second coil 50b, and the source of the seventh switch Q7 and the drain of the eighth switch Q8 are connected to the second end of the second coil 50b.

[0018] 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 is higher than that of the second end, an induced voltage is generated in the second coil 50b such that the potential of the first end is higher than that of the second end. On the other hand, when the potential of the second end of the first coil 50a is higher than that of the first end, an induced voltage is generated in the second coil 50b such that the potential of the second end is higher than that of the first end.

[0019] 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 considered positive when a discharge current flows through the storage battery 10 and negative when a charging current flows.

[0020] The second current sensor 62 detects a second current I2 flowing through the second high potential side terminal CH2, and the second voltage sensor 63 detects a second voltage V2 which is the 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 current flows in the drain direction of the fifth switch Q5 and the seventh switch Q7 from the second high potential side terminal CH2, and negative when current flows in the opposite direction.

[0021] The temperature sensor 64 detects the ambient temperature T. Here, in the present embodiment, the ambient temperature T is the temperature of the element to be heated. The element to be heated is, for example, the power conversion device 20 or the storage battery 10.

[0022] Each detected value I1, V1, I2, V2, T is input to a control unit 70 provided in the power conversion device 20. Based on each detected value I1, V1, I2, V2, T, the control unit 70 outputs a gate voltage Vg to the gates of the switches Q1 to Q8 and executes switching control of the switches Q1 to Q8.

[0023] Next, the temperature increase control implemented in the present embodiment will be described. In the present embodiment, the temperature increase 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 the input-side full-bridge circuit, and by executing switching control of the first to fourth switches Q1 to Q4 as input-side switches, the DC voltage input from the storage battery 10 is converted into an AC voltage and applied to the first coil 50a. Also, the second full-bridge circuit 40 corresponds to the output-side full-bridge circuit, and by executing switching control of the fifth to eighth switches Q5 to Q8 as output-side switches, the AC voltage output from the second coil 50b is converted into a DC voltage and output to the power supply target 11.

[0024] In the temperature increase control, when the ambient temperature T is higher than the set temperature, it is set to the normal mode assuming that there is no requirement to increase the amount of heat generated by the switch with the execution of switching control. On the other hand, when the ambient temperature T is below the set temperature, it is set to the heat generation mode assuming that there is a requirement to increase.

[0025] Using FIG. 2, first, the switching control in the normal mode performed by the control unit 70 will be described.

[0026] The command current setting unit 71 includes a current calculation unit 72 and a minimum value selection unit 73. The current calculation unit 72 calculates a command current I2f by dividing the target power value PW* by the second voltage V2 which is the detected voltage of the second voltage sensor 63. The definition of the sign of the command current I2f is the same as the definition of the sign of the second current I2.

[0027] The minimum value selection unit 73 selects, as the final command current Iref2, the one with the smaller absolute value between the command current I2f calculated by the current calculation unit 72 and the current command value I2*. The current command value I2* is set, for example, to the upper limit value of the current value that can flow through the first full-bridge circuit 30. The command current Iref2 output from the minimum value selection unit 73 is limited by the first limiter 74 to an upper limit value or a lower limit value.

[0028] 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 detected current of the second current sensor 62 from the command current Iref2 output from the first limiter 74.

[0029] The first feedback control unit 77 calculates a port-to-port phase φ21 as an operation amount for feeding back the calculated current deviation ΔI2 to zero. In this embodiment, as this feedback control, proportional-integral control using a positive feedback gain is executed. 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.

[0030] The inter-port phase φ21 calculated by the first feedback control unit 77 is limited to an upper limit value or a lower limit value by the second limiter 78. In the present embodiment, the inter-port phase φ21 is set in the range from -90° to 90°. The sign of the inter-port phase φ21 represents the power transmission direction. However, in the present embodiment, an example in which power is transmitted in the direction from the first full-bridge circuit 30 to the second full-bridge circuit 40 will be described. Therefore, hereinafter, the inter-port phase φ21 is set to a value in the range from 0° to 90°. The greater the inter-port phase φ21, the greater the transmitted power from the storage battery 10 to the power supply target 11.

[0031] The PWM generation 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 them to the gate voltage drive unit 80. The PWM generation unit 79 generates drive signals SD for the first to fourth switches Q1 to Q4 for alternately turning on the pair of the first and fourth switches Q1 and Q4 and the pair of the second and third switches Q2 and Q3. Also, the PWM generation unit 79 generates drive signals SD for the fifth to eighth switches Q5 to Q8 for alternately turning on the pair of the fifth and eighth switches Q5 and Q8 and the pair of the sixth and seventh switches Q6 and Q7. In the present embodiment, one switching period Tsw of each of the switches Q1 to Q8 is the same as each other. Also, the duty ratio (= Ton / Tsw), which is the ratio of the on-period Ton to one switching period Tsw of each of the switches Q1 to Q8, is also the same value (for example, 0.5) for each other. The PWM generation unit 79 generates drive signals SD for each of the switches Q1 to Q8 such that the switching timing to the on-state of the fifth switch Q5 is the timing advanced by the inter-port phase φ21 output from the second limiter 78 with respect to the switching timing to the on-state of the first and fourth switches Q1 and Q4.

[0032] Power transmission from the storage battery 10 to the power supply target 11 is performed on 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 transmission is performed is a period in which the polarities of the voltages applied from the first full-bridge circuit 30 to the first coil 50a and from the second full-bridge circuit 40 to the second coil 50b are the same.

[0033] 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, power (active power) transmission from the storage battery 10 to the power supply target 11 is not performed. The period during which power transmission is not performed is a reverse polarity period in which the polarities of the voltages applied from the first full-bridge circuit 30 to the first coil 50a and from the second full-bridge circuit 40 to the second coil 50b are opposite.

[0034] Based on the input drive signal SD, the gate voltage drive unit 80 outputs a gate voltage Vg to the gates of the switches Q1 to Q8. In this case, the gate voltage drive unit 80 sets the gate voltage Von when turning on the switches Q1 to Q8 to a first on voltage Vα that is equal to or higher than the threshold voltage Vth of the switches Q1 to Q8. When the first on voltage Vα is input, the switches Q1 to Q8 are in a full-on state.

[0035] Subsequently, the heating mode will be described.

[0036] Based on the output drive signal SD, the gate voltage driver 80 outputs a gate voltage Vg to the gates of the switches Q1 to Q8. In the heat generation mode, when the gate voltage driver 80 turns on the fifth to eighth switches Q5 to Q8, it sets the gate voltage Von to the first on-voltage Vα. On the other hand, when the gate voltage driver 80 turns on the first to fourth switches Q1 to Q4, it sets the gate voltage Von to a second on-voltage Vβ (≥ Vth) that is lower than the first on-voltage Vα.

[0037] That is, in the heat generation mode, the gate voltage Von when turning on the first to fourth switches Q1 to Q4 is lower than when executing the normal mode. When the second on-voltage Vβ is applied to the gate, the first to fourth switches Q1 to Q4 are in a half-on state. The on-resistance of the switch in the half-on state is larger than that of the switch in the full-on state. As a result, the conduction loss generated in the switch in the half-on state is larger than the conduction loss generated in the switch in the full-on state. Thus, the amount of heat generated in the first to fourth switches Q1 to Q4 in the heat generation mode is larger than the amount of heat generated in the first to fourth switches Q1 to Q4 in the normal mode.

[0038] Fig. 3 shows the circuit configuration of the gate voltage driver 80. In Fig. 3, the gate voltage driver 80 corresponding to the first switch Q1 is taken as an example for explanation. Note that the gate voltage drivers 80 corresponding to the second to eighth switches Q2 to Q8 are omitted from the explanation because they basically have the same configuration as the gate voltage driver 80 corresponding to the first switch Q1.

[0039] The gate voltage driver 80 includes a charging resistor RC and a discharging resistor RD. One end of the charging resistor RC is connected to the first power supply PS1 via a charging switch SWC, and the other end of the charging resistor RC is connected to the gate of the first switch Q1 via a charge and discharge path LA. One end of the discharging resistor RD is connected to the gate of the first switch Q1 via the charge and discharge path LA, and the other end of the discharging resistor RD is connected to the source of the first switch Q1 via a discharging switch SWC.

[0040] A drive signal SD corresponding to the first switch Q1 is input to the gate of the charging switch SWC, and a logical inversion signal SR of the drive signal SD is input to the gate of the discharge switch SWC by the inversion circuit CR. When the drive signal SD becomes an on signal, the charging switch SWC becomes an on state and the discharge switch SWC becomes an off state. 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 becomes an on state.

[0041] On the other hand, when the drive signal SD becomes an off signal, the charging switch SWC becomes an off state and the discharge switch SWC becomes an off state. In this case, charge flows out from the gate of the first switch Q1 to the source through the charge-discharge path LA and the discharge switch SWC. As a result, the gate voltage Vg of the first switch Q1 becomes less than the threshold voltage Vth, and the first switch Q1 becomes an off state.

[0042] The gate voltage driving unit 80 includes a series connection body of a first voltage dividing resistor Rb1 and a second voltage dividing resistor Rb2 (corresponding to a "voltage detection unit"). The drain and source of the first switch Q1 are connected by this series connection body.

[0043] The gate voltage driving unit 80 includes an operational amplifier CP, first to fifth resistors R1 to R5, a Zener diode DT, a switching switch SWK, and an adjustment switch SWN.

[0044] The inverting input terminal of the operational amplifier CP is connected to the connection point of the first voltage dividing resistor Rb1 and the second voltage dividing resistor Rb2 via the first resistor R1. The voltage Vds between the main terminals of the first switch Q1 (drain-source voltage) is divided by the first voltage dividing resistor Rb1 and the second voltage dividing 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 (corresponding to a "power supply unit") via the connection path LB.

[0045] A second resistor R2 is provided in the connection path LB. The non-inverting input terminal side of the operational amplifier CP with respect to the second resistor R2 in the connection path LB is connected to the source (low-voltage side terminal) of the first switch Q1 by the zener diode DT and the third drive switch SW3, respectively. 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 of the first switch Q1. The switching switch SWK is an N-channel MOSFET, and the drain of the switching switch SWK is connected to the connection path LB. The source of the switching switch SWK is connected to the source of the first switch Q1.

[0046] The output terminal of the operational amplifier CP is connected to the source of the first switch Q1 via a series connection of the third resistor R3 and the fourth resistor R4. The inverting input terminal and the output terminal are connected by a series connection of the fifth resistor R5 and the capacitor CN as a phase compensation circuit.

[0047] The adjustment switch SWN is an NPN bipolar transistor. 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 and 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 the output signal ST output from the output terminal of the operational amplifier CP. When the adjustment switch SWN is turned on, charge is extracted from the gate of the first switch Q1 via the charge and discharge path LA. In this embodiment, the third resistor R3, the fourth resistor R4, the diode DI, and the adjustment switch SWN correspond to a "voltage adjustment unit".

[0048] 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 of the third power supply PS3 and the source potential. The control unit 70 switches the changeover switch SWK to the on state in the 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 off the adjustment switch SWN. As a result, the adjustment switch SWN is turned off. As a result, the gate voltage Von when the first switch Q1 is turned on becomes the first on voltage Vα.

[0049] On the other hand, the control unit 70 switches the changeover switch SWK to the off state in the heat generation mode. In this case, the target value Vs* is applied to the non-inverting input terminal of the operational amplifier CP. Here, the target value Vs* is the breakdown voltage of the Zener diode DT. The target value Vs* is set to the divided voltage Vs corresponding to the range of the drain-source voltage Vds that changes as the gate voltage Vgs changes in the characteristic (the characteristic shown in FIG. 4) indicating the relationship between the gate voltage Vgs of the first switch Q1 and the drain-source voltage Vds between the main terminals of the first switch Q1.

[0050] A range that is lower than the drain-source voltage Vds of the first switch Q1 when the gate voltage Vgs of the first switch Q1 is the threshold voltage Vth of the first switch Q1 and higher than 1 / 100 of the upper limit value of the drain-source voltage that the first switch Q1 can obtain (400 V in FIG. 4) is defined as the appropriate voltage range. In the present embodiment, this upper limit value is the output voltage of the storage battery 10. In this case, the target value Vs* only needs to be set to the divided voltage Vs corresponding to the above appropriate voltage range.

[0051] Here, with reference to FIG. 4, the target value Vs* will be described. FIG. 4(A) is a characteristic diagram showing the relationship between the drain-source voltage Vds and the gate voltage Vgs of each of the switches Q1 to Q8. FIG. 4(B) is an enlarged view of a portion of the characteristic diagram shown in FIG. 4(A) where the gate voltage Vgs is around 2.69 V. Hereinafter, the description will be made taking the first switch Q1 as an example. Note that in FIG. 4, it is assumed that the drain-source current Ids flowing through the switch and the temperature of the switch are constant.

[0052] In the normal mode, in order to perform high-efficiency driving with low conduction loss, a first on-voltage Vα that is sufficiently high (for example, a voltage of 4 V or higher) is applied to the gate of the first switch Q1. In this case, the voltage Vds between the main terminals of the first switch Q1 decreases to near 0 V.

[0053] On the other hand, when the gate voltage is decreased from the first on-voltage Vα, at around 2.8 V, the voltage Vds between the main terminals rapidly increases, and the on-resistance of the first switch Q1 also increases. In the example shown in FIG. 4, when the gate voltage is further decreased and the gate voltage becomes around 2.69 V, the voltage Vds between the main terminals when the first switch Q1 is in the off state (that is, a value near the voltage between the terminals of the battery 10) is obtained.

[0054] Based on the characteristics shown in FIG. 4, the appropriate gate voltage range (for example, 2.690 to 2.7 V. ΔVg = 0.01 V) for increasing the amount of heat is extremely narrow compared to the voltage range of the voltage Vds between the main terminals of the first switch Q1 corresponding to that voltage range (for example, 50 to 300 V. ΔVg = 250 V). Specifically, it is 1 / 10000 or less of the voltage range of the voltage Vds between the main terminals. In this gate voltage range, the change amount of the on-resistance per unit change amount of the gate voltage Vgs is large. Here, the appropriate gate voltage range for increasing the amount of heat depends on the temperature of the first switch Q1, individual differences in manufacturing, and the like. Therefore, even when the deviation of the actual gate voltage with respect to the above appropriate gate voltage range is small, there is a concern that the on-resistance will greatly decrease with respect to the assumed value. In this case, there is a concern that the amount of heat generated in the first switch Q1 will greatly decrease.

[0055] Therefore, in this embodiment, instead of a configuration that controls the actual gate voltage to the target value of an appropriate gate voltage to increase the calorific value, a configuration that controls the actual voltage between the main terminals to the target value of an appropriate voltage between the main terminals to increase the calorific value is used. Thereby, the on-resistance of the first switch Q1 can be adjusted with high precision. Note that the appropriate gate voltage range for increasing the calorific value is not limited to 1 / 10000 or less of the voltage range of the voltage Vds between the main terminals of the first switch Q1 corresponding to that voltage range, and may be, for example, 1 / 1000 or less, 1 / 100 or less, or 1 / 10 or less. In other words, the appropriate gate voltage range for increasing the calorific value is not limited to a range four orders of magnitude smaller than the voltage range of the voltage Vds between the main terminals of the first switch Q1 corresponding to that voltage range, and may be, for example, a range three orders of magnitude, two orders of magnitude, or one order of magnitude smaller.

[0056] According to the configuration described above, even if a deviation of the divided voltage Vs from the target value Vs* occurs, the on-resistance in the heat generation mode does not significantly decrease with respect to the assumed value, and the calorific value generated in the first switch Q1 can be appropriately increased.

[0057] FIG. 5 shows the transition of the driving state and the like of the first switch Q1 in the normal mode and the heat generation mode. FIGS. 5(A) and (C) show the transition of the driving states of the first and fifth switches Q1 and Q5, and FIGS. 5(B) and (D) show the transition of the voltages Vds between the main terminals of the first and fifth switches Q1 and Q5. FIG. 5(E) shows the transition of the currents Ids1 and Ids5 flowing through the voltages between the main terminals of the first and fifth switches Q1 and Q5, and FIG. 5(F) shows the transition of the conduction loss generated in the first switch Q1. In FIG. 5, the normal mode is implemented at times t1 to t2, and the heat generation mode is implemented at times t2 to t3. Also, in FIG. 5, Tsw indicates the switching period of each switch.

[0058] In the example shown in FIG. 5, in the normal mode, when turning on the first to fourth switches Q1 to Q4, the first on-voltage Vα is applied as the gate voltage Von. In this case, the voltage Vds between the main terminals of the first to fourth switches Q1 to Q4 becomes substantially zero.

[0059] On the other hand, in the heat generation mode, when turning on the first to fourth switches Q1 to Q4, the second on-voltage Vβ (<Vα) is applied as the gate voltage Von. Therefore, for example, 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 normal mode is performed, and the conduction loss generated in the first switch Q1 increases significantly. As a result, as shown in FIG. 6(A), the amount of heat generated in the first to fourth switches Q1 to Q4 can be greatly increased.

[0060] In contrast, in the comparative example shown in FIG. 6(B), the conduction losses of the third and fourth switches Q3 and Q4 are greatly reduced, and the amount of heat cannot be greatly increased. The comparative example is a configuration that does not have a configuration for feedback control of the divided voltage detection value of the voltage between the drain and source of the switch to the target value, but a configuration for feedforward control of the gate voltage detection value to the target value. Also, KL in FIG. 6 indicates the common scale of one grid of the vertical axis in (A) and (B).

[0061] According to the present embodiment described above, even when the voltage-current characteristics of the first to fourth switches Q1 to Q4 depend on the temperature of the switches, individual differences in manufacturing, etc., the amount of heat generated in the first to fourth switches Q1 to Q4 in the heat generation mode can be greatly increased. Also, the amount of heat generated in the first to fourth switches Q1 to Q4 can be balanced as much as possible. Therefore, it is possible to suppress the occurrence of a situation in which heat generation is concentrated in some of the first to fourth switches Q1 to Q4 and an overheating state occurs.

[0062] When performing feedback control of the divided voltage Vs of the voltage Vds between the main terminals to the target value Vs*, an operational amplifier CP that processes an analog signal, which is a continuous value, is used. Therefore, compared with the case where a digital circuit that processes a digital signal, which is a discrete value, is used, it is possible to improve the adjustment accuracy of the amount of charge extracted from the gates of the first to fourth switches Q1 to Q4 by driving the adjustment switch SWN. As a result, the divided voltage Vs can be accurately converged to the target value V*, and thus the amount of heat generation can be adjusted with high precision.

[0063] No adjustment unit for gate charge amount is provided on the charge and discharge path LA. As a result, an increase in impedance on the charge and discharge path LA can be suppressed. Consequently, while preventing the switching control of the first to fourth switches Q1 to Q4 from becoming unstable, the gate voltages of the first to fourth switches Q1 to Q4 can be adjusted to appropriate voltages for increasing the amount of heat generation.

[0064] By turning on or off the changeover switch SWK, the value input to the operational amplifier CP is switched to the target value Vs* or 0. As a result, the heat generation mode or the normal mode can be easily switched.

[0065] <Second Embodiment> Hereinafter, the second embodiment will be described with reference to the drawings, centering on the differences from the first embodiment. In this embodiment, the power supply voltage applied from the first power supply PS1 to the gates of the first to fourth switches Q1 to Q4 is adjusted to adjust the amount of charge flowing into the gates.

[0066] Fig. 7 shows the gate voltage driving unit 80 and its peripheral configuration. In Fig. 7, the gate voltage driving unit 80 corresponding to the first switch Q1 will be described as an example. Note that the gate voltage driving units 80 corresponding to the second to eighth switches Q2 to Q8 are basically the same in configuration as the gate voltage driving unit 80 corresponding to the first switch Q1, and thus the description thereof will be omitted. Also, in Fig. 7, the same components as those shown in Fig. 3 above are given the same reference numerals for convenience.

[0067] The control unit 70 includes a voltage calculation unit 90. The voltage calculation unit 90 includes an AD converter 91, a voltage deviation calculation unit 92, a feedback control unit 93, a switching unit 94, and a target voltage calculation unit 95. Incidentally, in this embodiment, the voltage calculation unit 90 is composed of a digital circuit. As a result, the construction of the control system becomes easier than in the case of an analog circuit, and the configuration of the voltage calculation unit 90 can be simplified.

[0068] The AD converter 91 converts the divided voltage Vs, which is an analog signal, into a digital signal. The voltage deviation calculation unit 92 calculates a voltage deviation ΔVs by subtracting the divided voltage Vs of the digital signal output from the AD converter 91 from the target value Vs*.

[0069] The feedback control unit 93 calculates a feedback command voltage Vfb as an operation amount for feeding back the calculated voltage deviation ΔVs to 0. In this embodiment, proportional-integral control is used as this feedback control. Note that the feedback control is not limited to proportional-integral control, and may be, for example, proportional-integral-derivative control.

[0070] The switching unit 94 outputs either the feedback command voltage Vfb calculated by the feedback control unit 93 or 0V as the command voltage Vref based on the mode signal SM generated by the control unit 70. The mode signal SM is a signal that switches between the case where the control mode is the heat generation mode and the case where it is the normal mode. When the switching unit 94 determines that the normal mode is to be implemented based on the mode signal SM, it sets the command voltage Vref to 0V. On the other hand, when the switching unit 94 determines that the heat generation mode is to be implemented based on the mode signal SM, it sets the command voltage Vref to the feedback command voltage Vfb.

[0071] The target voltage calculation unit 95 calculates a target power supply voltage Vоn* by subtracting the command voltage Vref output from the switching unit 94 from the first on-voltage Vα. The first power supply PS1 is controlled such that the output voltage becomes the target power supply voltage Vоn* calculated by the target voltage calculation unit 95. Therefore, in the normal mode, the command voltage Vref is set to 0, and the gate voltage Von when the first switch Q1 is turned on is the first on-voltage Vα. On the other hand, in the heat generation mode, the command voltage Vref is the feedback command voltage Vfb, and the gate voltage Von when the first switch Q1 is turned on is the second on-voltage Vβ (= Vα - Vfb).

[0072] According to the present embodiment described above, while reducing the number of additional components to the gate voltage driving unit 80, the gate voltage of the first switch Q1 can be accurately adjusted to an appropriate voltage for increasing the heat generation amount with high precision.

[0073] <Third Embodiment> Hereinafter, in the third to fifth embodiments, another example of the power conversion device will be described. First, the third embodiment will be described with reference to the drawings centering 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, but this is changed. In this embodiment, as shown in FIG. 8, the configuration of the power conversion device 20 is a phase-shifted full-bridge circuit. In FIG. 8, the same components as those shown in the previous FIG. 1 are given the same reference numerals for convenience.

[0074] As shown in FIG. 8, the switch unit 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.

[0075] The anode of the first diode DI1 is connected to the first end of the second coil 50b, and the second low-potential side terminal CL2 is connected to the second end of the second coil 50b. The second low-potential side terminal CL2 is connected to the first end of the third coil 50c, and the anode of the second diode DI2 is connected to the second end of the third coil 50c. The first end of the reactor 101 is connected to the cathodes of the first and second diodes DI1 and DI2, and the second high-potential side terminal CH2 is connected to the second end of the reactor 101.

[0076] 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 with respect to the second end becomes higher, an induced voltage is generated in the third coil 50c such that the potential of the second end is higher than that of the first end. On the other hand, when the potential of the second end of the first coil 50a with respect to the first end becomes higher, an induced voltage is generated in the third coil 50c such that the potential of the second end is lower than that of the first end.

[0077] Based on each detected value I1, V1, I2, V2, T, the control unit 70 outputs a gate voltage Vg to the gates of the first to fourth switches Q1 to Q4 to turn the first to fourth switches Q1 to Q4 on and off.

[0078] <Fourth Embodiment> Hereinafter, the fourth embodiment will be described with reference to the drawings, centering on the differences from the first embodiment. In the first embodiment, a full-bridge circuit was used in the configuration of the power conversion device 20, but this is changed. In this embodiment, as shown in FIG. 9, the configuration of the power conversion device 20 is a boost chopper circuit. In FIG. 9, the same components as those shown in the previous FIG. 1 are given the same reference numerals for convenience.

[0079] As shown in FIG. 9, the switch unit 21 includes a reactor 102 and a half-bridge circuit 103.

[0080] The half-bridge circuit 103 includes an eleventh switch Q11 and a twelfth switch Q12. In the present embodiment, the eleventh and twelfth switches Q11 and Q12 are IGBTs. The second high potential side terminal CH2 is connected to the collector of the eleventh switch Q11. The collector of the twelfth switch Q12 is connected to the emitter of the eleventh switch Q11. The first low potential side terminal CL1 and the second low potential side terminal CL2 are connected to the emitter of the twelfth switch Q12. Freewheeling diodes are connected in anti-parallel to the eleventh and twelfth switches Q11 and Q12.

[0081] The first end of the reactor 102 is connected to the first high potential side terminal CH1. The second end of the reactor 102 is connected to the emitter of the eleventh switch Q11 and the collector of the twelfth switch Q12.

[0082] Based on each detected value I1, V1, I2, V2, T, the control unit 70 outputs a gate voltage Vg to the gates of the eleventh and twelfth switches Q11 and Q12 to turn on and off the eleventh and twelfth switches Q11 and Q12. The control unit 70 calculates the duty ratio of the eleventh switch Q11 in order to perform feedback control on the current flowing through the reactor 102 to a target current.

[0083] <Fifth Embodiment> Hereinafter, the fifth embodiment will be described with reference to the drawings, centering on the differences from the first embodiment. In the first embodiment, a full-bridge circuit was used in the configuration of the power conversion device 20, but this is changed. In the present embodiment, as shown in FIG. 10, the configuration of the power conversion device 20 is a three-phase inverter circuit. In FIG. 10, the same components as those shown in the previous FIG. 1 are given the same reference numerals for convenience.

[0084] As shown in FIG. 10, the power conversion system includes a storage battery 10, a rotating electrical machine 120 as a power supply target, a high potential side terminal CH1, 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. The power conversion device 20 includes an inverter 104 as a switch unit.

[0085] The rotating electrical machine 120 is a brushless synchronous machine, for example, a permanent magnet synchronous machine. The rotating electrical machine 120 includes three-phase armature windings, i.e., U-phase, V-phase, and W-phase windings 121U, 121V, and 121W.

[0086] The rotating electrical machine 120 is connected to the storage battery 10 via the inverter 104. The inverter 104 includes series-connected bodies of upper arm switches QUH, QVH, QWH and lower arm switches QUL, QVL, QWL. The first end of the U-phase winding 121U is connected to the connection point of the U-phase upper and lower arm switches QUH and QUL via the U-phase terminal CNU. The first end of the V-phase winding 121V is connected to the connection point of the V-phase upper and lower arm switches QVH and QVL via the V-phase terminal CNV. The first end of the W-phase winding 121W is connected to the connection point of the W-phase upper and lower arm switches QWH and QWL via the W-phase terminal CNW. The second ends of the U-phase, V-phase, and W-phase windings 121U, 121V, and 121W are connected at the neutral point PT. In the present embodiment, IGBTs are used as the switches QUH to QWL, and freewheel diodes are connected in anti-parallel to the switches QUH to QWL.

[0087] A capacitor 105 is provided on the storage battery 10 side of the inverter 104 rather than on the side of the switches QUH to QWL. The high-potential side terminal of the capacitor 105 is connected to the high-potential side terminal CH, and the low-potential side terminal of the capacitor 105 is connected to the low-potential side terminal CL. Note that the capacitor 105 may be provided outside the inverter 104.

[0088] The power conversion device 20 includes a current sensor 106. The current sensor 106 detects currents of at least two phases among the phase currents IU, IV, and IW flowing through the rotating electrical machine 120.

[0089] Based on each detection value IU, IV, IW, T, the control unit 70 outputs a gate voltage Vg to the gates of the switches QUH to QWL to turn on and off each switch QUH to QWL. The control unit 70 performs switching control of the switches SUH to SWL to perform feedback control of the control amount (for example, torque) of the rotating electrical machine 120 to a command value.

[0090] <Sixth Embodiment> Hereinafter, the sixth embodiment will be described with reference to the drawings, centering on the differences from the first embodiment. In the present embodiment, as shown in FIG. 11, a heat transfer unit 110 is added to the configuration of the first embodiment. In FIG. 11, the same components as those shown in FIG. 1 are given the same reference numerals for convenience.

[0091] The heat transfer unit 110 is configured to be able to absorb the heat generated by the heat exchange target elements, with each switch Q1 to Q8, the transformer 50, and the power supply target 11 as the heat exchange target elements. The heat transfer unit 110 transfers the absorbed heat to the temperature-rising target element to raise the temperature of the temperature-rising target element. The temperature-rising target element is, for example, the power supply target 11.

[0092] As the heat transfer unit 110, for example, it may be provided with a circulation path through which cooling water circulates between the heat exchange target element and the temperature-rising target element, and the temperature-rising target element is heated through this cooling water. In addition, as the heat transfer unit 110, for example, a gas (air) may be used as the cooling fluid. Further, as the heat transfer unit 110, for example, it may be a component member such as a heat sink that contacts the heat exchange target element and the temperature-rising target element without using a cooling fluid.

[0093] According to the present embodiment described above, since the heat generated during power conversion can be recovered and transferred to the temperature-rising target element, the temperature of the temperature-rising target element can be efficiently increased.

[0094] <Other Embodiments> Note that each of the above embodiments may be implemented with the following modifications.

[0095] · In the heating mode, the gate voltage Von when the fifth to eighth switches Q5 to Q8 are turned on may be the second on-voltage Vβ.

[0096] · The configuration of the power conversion device 20 is not limited to those shown in the first embodiment, the fourth embodiment, the fifth embodiment, and the sixth embodiment, and may be a forward-type DCDC converter, an LLC-type DCDC converter, a single-phase DCAC inverter, or the like.

[0097] · In the second embodiment, the voltage calculation unit 90 may be configured by an analog circuit.

[0098] · The control unit and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Or, the control unit and its method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured by one or more hardware logic circuits. Also, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer.

Description of Reference Numerals

[0099] 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 side terminals (CH1, CL1), output side terminals (CH2, CL2), and a switch section (21, 104), and transferring power input from the input side terminals to the output side terminals by performing switching control of the switch section, a requirement determination section for determining whether there is an increasing requirement for the amount of heat generated in the switch section with the execution of the switching control; a gate control section (CP, R3, R4, DI, SWN, PS1, LA, SWK, 90) that sets the gate voltage of the switch section to a first on voltage equal to or higher than the threshold voltage of the switch section when turning on the switch section when it is determined that there is no such increasing requirement, and sets the gate voltage to a second on voltage that is equal to or higher than the threshold voltage and lower than the first on voltage when turning on the switch section when it is determined that there is such increasing requirement; a voltage detection section (Rb1, Rb2) for detecting the voltage between the main terminals of the switch section, and when it is determined that there is such increasing requirement and the switch section is to be turned on, the gate control section operates the gate voltage of the switch section to perform feedback control of the detected voltage between the main terminals to a target value. The target value is set to be lower than the voltage between the main terminals when the gate voltage is the threshold voltage and higher than the voltage between the main terminals when the gate voltage is the first on voltage. In the characteristic of the voltage between the main terminals with respect to the gate voltage, the amount of change in the voltage between the main terminals when the gate voltage changes from the threshold voltage to the first on voltage is larger than the range of the gate voltage from the threshold voltage to the first on voltage. A power conversion device.

2. The gate control section includes an operational amplifier (CP) having a pair of input terminals, to which the voltage between the main terminals detected at one of the input terminals is input and the target value is input to the other terminal, and a voltage adjustment section (R3, R4, DI, SWN) that adjusts the gate voltage of the switch section based on the output signal of the operational amplifier to perform feedback control of the detected voltage between the main terminals to the target value. The power conversion device according to claim 1.

3. The gate control section includes a power supply section (PS1) that generates a power supply voltage for turning on the switch section. A charging path (LA) interposed between the power supply unit and the gate of the switch unit; comprising; the voltage adjustment unit; is connected to the low-potential side terminal of the pair of main terminals of the switch unit and the charging path; The power conversion device according to claim 2, wherein the detected voltage between the main terminals is feedback-controlled to the target value by adjusting the amount of charge extracted from the gate of the switch unit through the charging path based on the output signal of the operational amplifier.

4. The gate control unit; comprises a switching switch (SWK) that connects the terminal to which the target value is input among the input terminals of the operational amplifier and the low-potential side terminal of the pair of main terminals of the switch unit; The power conversion device according to claim 2 or 3, wherein the switching switch is switched to the on state when it is determined that there is no increase requirement, and the switching switch is switched to the off state when it is determined that there is an increase requirement.

5. The gate control unit; a power supply unit (PS1) that generates a power supply voltage for turning on the switch unit; a charging path (LA) interposed between the power supply unit and the gate of the switch unit; a voltage calculation unit (90) that calculates the power supply voltage as an operation amount for feedback-controlling the detected voltage between the main terminals to the target value; comprising; The power conversion device according to claim 1, wherein the calculated power supply voltage is output to the gate through the charging path.

6. The power conversion device according to any one of claims 1 to 5, comprising a heat transfer unit (110) that absorbs heat generated during the switching control and transfers the heat to a temperature-rising target element.

7. In a program applied to a power conversion device (20) having input-side terminals (CH1, CL1), output-side terminals (CH2, CL2), and a switch unit (21, 104), and transmitting power input from the input-side terminals to the output-side terminals by performing switching control of the switch unit, the power conversion device; a voltage detection unit (Rb1, Rb2) that detects the voltage between the main terminals of the switch unit; a computer to which the voltage between the main terminals detected by the voltage detection unit is input; comprising; in the computer, a process for determining whether there is a requirement to increase the amount of heat generated in the switch unit during the execution of the switching control; When it is determined that there is no such increase request, the gate voltage of the switch section when turning on the switch section is set to a first on-voltage equal to or higher than the threshold voltage of the switch section. When it is determined that there is an increase request, the gate voltage when turning on the switch section is set to a second on-voltage that is equal to or higher than the threshold voltage and lower than the first on-voltage. This is a gate control process. Execute In the gate control process, when it is determined that there is an increase request and the switch section is turned on, the gate voltage of the switch section is manipulated to feedback-control the detected voltage between the main terminals to a target value. The target value is set to be lower than the voltage between the main terminals when the gate voltage is the threshold voltage, and higher than the voltage between the main terminals when the gate voltage is the first on-voltage. In the characteristic of the voltage between the main terminals with respect to the gate voltage, the amount of change in the voltage between the main terminals when the gate voltage changes from the threshold voltage to the first on-voltage is larger than the range of the gate voltage from the threshold voltage to the first on-voltage. Program.

Images