Heating system

Abstract

To provide technique which can generate heat by a switching element when the heat for heating is required.SOLUTION: A heating system uses heat generating by a switching element as the heat for heating. The heating system may comprise the switching element, a first heat transmission part which transmits the heat generating by the switching element to a heat transfer medium for heating and a control device which controls switching operation of the switching element. The control device may control the switching element by hard switching by switching over the switching method of the switching element when acquiring a prescribed heating request while controlling the switching element by soft switching.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The technology disclosed herein relates to heating systems. [Background technology]

[0002] Patent Document 1 discloses an air conditioner for an electric vehicle that uses an electric heater as a heat source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-238924 Summary of the Invention [Problem to be solved by the invention]

[0004] Although the air conditioner of Patent Document 1 uses an electric heater as a heat source, it is also possible to use a heat source other than an electric heater. For example, it is possible to use a switching element in an electronic device as a heat source. This specification provides a technology that can generate heat with a switching element when heat for heating is needed. [Means for solving the problem]

[0005] A first aspect of the present technology relates to a heating system that uses heat generated by a switching element as heat for heating. The heating system may include the switching element, a first heat transfer unit that transfers the heat generated by the switching element to a heat medium for heating, and a control device that controls a switching operation of the switching element. When a predetermined heating request is acquired while the control device is controlling the switching element by soft switching, the control device may switch a switching mode of the switching element to control the switching element by hard switching.

[0006] According to this configuration, when heat for heating is required, the switching mode of the switching element is switched to hard switching, which causes switching loss in the switching element and allows the heat generated thereby to be used for heating. By simply switching the switching mode of the switching element, heat for heating can be generated by the switching element.

[0007] In a second aspect, the heating system may include the switching element, a first heat transfer unit that transfers heat generated by the switching element to a heat medium for heating, and a control device that controls a switching operation of the switching element. When a predetermined heating request is acquired while synchronous rectification is being performed by periodically switching the switching element on and off, the control device may perform diode rectification by switching a switching method of the switching element and maintaining the switching element off.

[0008] According to this configuration, when heat for heating is needed, the switching mode of the switching element is switched to switch the rectification mode to diode rectification, which allows the switching element to generate switching loss and the heat generated thereby to be used for heating. Simply by switching the switching mode of the switching element, heat for heating can be generated by the switching element.

[0009] In a third aspect, in the first or second aspect, the heating system may further include a first temperature sensor that detects a temperature of the heat medium before it flows into the first heat transfer section. When acquiring the heating request, the control device may switch a switching mode of the switching element if the temperature detected by the first temperature sensor is less than a first threshold value.

[0010] According to this configuration, for example, when the temperature of the heat medium is high, soft switching can be performed, and when the temperature of the heat medium is low, hard switching can be performed. Also, when the temperature of the heat medium is high, synchronous rectification can be performed, and when the temperature of the heat medium is low, diode rectification can be performed. This allows the switching element to generate heat for heating according to the temperature of the heat medium.

[0011] In a fourth aspect, the heating system in the third aspect may be mounted on a vehicle. The heating system may further include a second heat transfer section that transfers heat generated by an engine of the vehicle to a heat medium for heating. The first temperature sensor may detect a temperature of the heat medium before it flows into the first heat transfer section and after it flows out of the second heat transfer section.

[0012] It is considered that the temperature of the heat medium after the heat generated by the engine is transferred thereto is high. According to the above-mentioned configuration, for example, when the temperature of the heat medium after the heat generated by the engine is transferred thereto is high, soft switching and / or synchronous rectification can be performed. On the other hand, even if the temperature of the heat medium after the heat generated by the engine is transferred thereto is low, hard switching and / or diode rectification can be performed. Therefore, heat for heating can be generated by the switching element according to the state of heat reception from the engine.

[0013] In a fifth aspect, in any one of the first to fourth aspects, the heating system may further include a second temperature sensor that detects a temperature of the switching element or a temperature of a board on which the switching element is mounted. When acquiring the heating request, the control device may switch a switching mode of the switching element if the temperature detected by the second temperature sensor is lower than a second threshold value.

[0014] According to this configuration, for example, when the temperature of the switching element or the temperature of the board on which the switching element is mounted is high, soft switching and / or synchronous rectification can be performed. This makes it possible to prevent overheating of the switching element and protect the switching element. Also, for example, when the temperature of the switching element or the temperature of the board on which the switching element is mounted is low, hard switching and / or diode rectification can be performed. This makes it possible for the switching element to generate heat for heating while preventing overheating of the switching element. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating a heating system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating a converter according to an embodiment of the present invention; [Diagram 3] 4 is a flowchart of a heating process according to the embodiment. [Figure 4] FIG. 13 is a diagram illustrating a converter according to a modified example. [Diagram 5] FIG. 13 is a diagram illustrating a heating system according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A heating system 2 of the embodiment will be described with reference to the drawings. As shown in FIG. 1, the heating system 2 of the embodiment is mounted on a vehicle 4. The heating system 2 can heat the interior (not shown) of the vehicle 4. The vehicle 4 on which the heating system 2 is mounted is, for example, a gasoline-powered automobile or a hybrid automobile. The vehicle 4 includes, for example, an engine 6, electronic equipment 8, a heater core 38, and a radiator 36.

[0017] The heating system 2 includes an engine 6 mounted on a vehicle 4, an electronic device 8, a heater core 38, and a radiator 36. The heating system 2 also includes a first circulation flow path 10, a second circulation flow path 12, and a control device 100.

[0018] The first circulation flow path 10 of the heating system 2 circulates coolant (an example of a heat medium for heating) between the engine 6, the electronic device 8, and the heater core 38. The second circulation flow path 12 circulates coolant between the engine 6 and the radiator 36. The upstream ends of the first circulation flow path 10 and the second circulation flow path 12 join together. The downstream ends of the first circulation flow path 10 and the second circulation flow path 12 join together. The upstream and downstream ends of the first circulation flow path 10 and the second circulation flow path 12 are connected to the engine 6.

[0019] A pump 30 is provided at the joint of the downstream end of the first circulation flow path 10 and the second circulation flow path 12. The pump 30 is disposed upstream of the engine 6 in the flow direction of the cooling water. The pump 30 pumps the cooling water flowing through the first circulation flow path 10 and the second circulation flow path 12 downstream.

[0020] A thermostat 32 is provided at a branching portion at the upstream end of the first circulation flow path 10 and the second circulation flow path 12. The thermostat 32 is disposed downstream of the engine 6 in the flow direction of the cooling water. The thermostat 32 adjusts the flow rate of the cooling water flowing through the first circulation flow path 10 and the second circulation flow path 12 according to the temperature of the cooling water. When the temperature of the cooling water is relatively high, the thermostat 32 relatively increases the flow rate of the cooling water flowing through the second circulation flow path 12 (relatively decreases the flow rate of the cooling water flowing through the first circulation flow path 10), and when the temperature of the cooling water is relatively low, the thermostat 32 relatively decreases the flow rate of the cooling water flowing through the second circulation flow path 12 (relatively increases the flow rate of the cooling water flowing through the first circulation flow path 10).

[0021] The engine 6 of the vehicle 4 includes, for example, a piston and a cylinder that houses the piston (neither is shown). The engine 6 generates driving force for the vehicle 4 by the piston moving up and down within the cylinder. When the engine 6 operates, heat is generated in the engine 6.

[0022] The engine 6 is provided with a cooling water passage 16 (an example of a second heat transfer section) through which cooling water flows for cooling the engine 6. The cooling water passage 16 is provided, for example, around the cylinder of the engine 6. Heat generated in the engine 6 is transferred to the cooling water flowing through the cooling water passage 16. The cooling water passage 16 constitutes a part of the first circulation passage 10. In addition, the cooling water passage 16 constitutes a part of the second circulation passage 12.

[0023] A coolant temperature sensor 24 (an example of a first temperature sensor) is attached to the first circulation flow path 10 between the engine 6 and the electronic device 8. The coolant temperature sensor 24 detects the temperature of the coolant flowing through the first circulation flow path 10 between the engine 6 and the electronic device 8. The coolant temperature sensor 24 detects the temperature of the coolant after it flows out of the coolant flow path 16 of the engine 6. The coolant temperature sensor 24 detects the temperature of the coolant before it flows into the coolant flow path 18 of the electronic device 8.

[0024] The electronic device 8 is disposed downstream of the engine 6 in the flow direction of the coolant. The electronic device 8 includes, for example, a DC-DC converter (hereinafter referred to as "converter") 20 for power conversion. The type of the electronic device 8 is not particularly limited. The converter 20 is, for example, a boost converter that boosts an input voltage and outputs it. In a modified example, the converter 20 may be a step-down converter that steps down an input voltage and outputs it.

[0025] The converter 20 will be described with reference to FIG. 2. As shown in FIG. 2, an input side (primary side) of the converter 20 is connected to, for example, a DC power source 40. The DC power source 40 applies a DC voltage to the converter 20. An output side (secondary side) of the converter 20 is connected to, for example, a secondary battery 90. In a modified example, the output side (secondary side) of the converter 20 may be connected to a load (not shown) of an electric product. The converter 20 boosts the voltage of the power source 40 and inputs it to the secondary battery 90 or the electric product. The secondary battery 90 stores the power supplied from the power source 40 via the converter 20. The electric product operates on the power supplied from the power source 40 via the converter 20.

[0026] The converter 20 includes a primary circuit 50, a secondary circuit 60, and a transformer 70 configured between the primary circuit 50 and the secondary circuit 60. The converter 20 of the embodiment is an isolated converter in which the primary circuit 50 and the secondary circuit 60 are insulated from each other. The converter 20 of the embodiment is a phase-shift full-bridge converter. This converter 20 is also called a DAB (Dual Active Bridge) converter. The type of the converter 20 is not particularly limited. The converter 20 may be a converter other than the phase-shift full-bridge converter. An example of the phase-shift full-bridge converter 20 will be described below.

[0027] The primary circuit 50 of the converter 20 includes a plurality of switching elements 51 - 54 , a primary coil 55 , a primary inductor 56 , and a primary capacitor 58 .

[0028] The multiple switching elements 51-54 include a first switching element 51, a second switching element 52, a third switching element 53, and a fourth switching element 54. In the converter 20, the multiple switching elements 51-54 are periodically switched on and off to convert a DC voltage on the input side (primary side) to a DC voltage on the output side (secondary side). In the following, of the multiple switching elements 51-54 of the primary side circuit 50, the first switching element 51 will be mainly described. The second switching element 52, the third switching element 53, and the fourth switching element 54 have the same configuration as the first switching element 51, so detailed description thereof will be omitted.

[0029] The first switching element 51 includes a transistor 51a and a diode 51b. The diode 51b may be a parasitic diode. The transistor 51a and the diode 51b are connected in parallel. The first switching element 51 is turned on / off by inputting a PWM (Pulse Width Modulation) signal to the transistor 51a, which turns the transistor 51a on / off. The same is true for the second switching element 52, the third switching element 53, and the fourth switching element 54. The multiple switching elements 51-54 are connected in series with a primary coil 55.

[0030] The primary coil 55 is wound around, for example, a metal core (not shown), and constitutes a transformer 70 together with the secondary coil 65. Power of the primary circuit 50 is transmitted to the secondary circuit 60 via the transformer 70. The primary inductance 56 is connected in series with the primary coil 55. The primary inductance 56 accumulates the energy of the current flowing through the primary circuit 50 and releases the accumulated energy. The primary capacitor 58 is connected in parallel with the primary inductance 56. The primary capacitor 58 accumulates the charge of the primary circuit 50 and releases the accumulated charge.

[0031] The secondary circuit 60 of the converter 20 includes a plurality of switching elements 61 - 64 , a secondary coil 65 , a secondary inductor 66 , and a secondary capacitor 68 .

[0032] The multiple switching elements 61-64 include a fifth switching element 61, a sixth switching element 62, a seventh switching element 63, and an eighth switching element 64. In the converter 20, the multiple switching elements 51-54 of the primary side circuit 50 are periodically switched on and off, and the multiple switching elements 61-64 of the secondary side circuit 60 are periodically switched on and off, thereby converting a DC voltage on the input side (primary side) into a DC voltage on the output side (secondary side). In the following, of the multiple switching elements 61-64 of the secondary side circuit 60, the fifth switching element 61 will be mainly described. The sixth switching element 62, the seventh switching element 63, and the eighth switching element 64 have the same configuration as the fifth switching element 61, so detailed description thereof will be omitted.

[0033] The fifth switching element 61 includes a transistor 61a and a diode 61b. The diode 61b may be a parasitic diode. The transistor 61a and the diode 61b are connected in parallel. The fifth switching element 61 is turned on / off by inputting a PWM (Pulse Width Modulation) signal to the transistor 61a, which turns the transistor 61a on / off. The same is true for the sixth switching element 62, the seventh switching element 63, and the eighth switching element 64. The multiple switching elements 61-64 are connected in series with the secondary coil 65.

[0034] The secondary coil 65 is wound around, for example, a metal core (not shown) and constitutes a transformer 70 together with the primary coil 55. The secondary inductance 66 is connected in series with the secondary coil 65. The secondary inductance 66 accumulates the energy of the current flowing through the secondary circuit 60 and releases the accumulated energy. The secondary capacitor 68 is connected in parallel with the secondary inductance 66. The secondary capacitor 68 accumulates the charge of the secondary circuit 60 and releases the accumulated charge.

[0035] The converter 20 generates heat by turning on and off the multiple switching elements 51-54, 61-64. The switching operation of each of the switching elements 51-54, 61-64 generates switching loss, which in turn generates heat in each of the switching elements 51-54, 61-64.

[0036] Returning to FIG. 1, the configuration of the heating system 2 will be described. As shown in FIG. 1, the electronic device 8 has a coolant flow path 18 (an example of a first heat transfer section) through which coolant flows. The coolant flow path 18 is provided, for example, around a converter 20. Heat generated in the converter 20 of the electronic device 8 is transferred to the coolant flowing through the coolant flow path 18. The coolant flow path 18 constitutes a part of the first circulation flow path 10.

[0037] The electronic device 8 further includes a converter temperature sensor 22 (an example of a second temperature sensor) that detects the temperature of the converter 20. The converter temperature sensor 22 can detect, for example, the temperature of a switching element (e.g., the first switching element 51) of the converter 20. Alternatively, the converter temperature sensor 22 can detect, for example, the temperature of a board (not shown) on which the switching element (e.g., the first switching element 51) of the converter 20 is mounted.

[0038] The heater core 38 is disposed downstream of the electronic device 8 in the coolant flow direction. The heater core 38 has a coolant flow path 38a through which the coolant flows. The coolant flow path 38a constitutes a part of the first circulation flow path 10. The heater core 38 is a heat exchanger that heats air by heat exchange between water and air. The heater core 38 heats the air inside the vehicle 4 by heat exchange between the coolant flowing through the coolant flow path 38a and the air inside the vehicle 4 sent by a fan 39. The air heated by the heater core 38 is sent to the interior of the vehicle 4, thereby heating the interior of the vehicle 4.

[0039] The radiator 36 is disposed downstream of the thermostat 32 in the flow direction of the coolant. The radiator 36 includes a coolant flow path 36a through which the coolant flows. The coolant flow path 36a constitutes a part of the second circulation flow path 12. The radiator 36 is a heat exchanger that cools water by heat exchange between water and air. The radiator 36 cools the coolant by heat exchange between the coolant flowing through the coolant flow path 36a and the air outside the vehicle 4 sent by a fan 37. The coolant cooled by the radiator 36 is sent to the engine 6 through the second circulation flow path 12, thereby cooling the engine 6.

[0040] The control device 100 of the heating system 2 includes, for example, a CPU, a ROM, and a RAM, and executes predetermined control and processing related to the heating system 2 based on a program stored in a storage device. The control and processing executed by the control device 100 will be described later.

[0041] In the heating system 2 described above, for example, when a heating switch (not shown) is turned on, the fan 39 starts. As a result, air heated by the heater core 38 is sent to the interior of the vehicle 4, and the interior of the vehicle 4 is heated.

[0042] (Heating treatment; Figure 3) The heating process of the embodiment will be described. The heating process of the embodiment is started, for example, when the engine 6 of the vehicle 4 is started. As shown in FIG. 3, in S10 of the heating process, the control device 100 monitors whether or not it acquires a predetermined heating request. The predetermined heating request is transmitted to the control device 100, for example, when a heating switch (not shown) of the vehicle 4 is turned on. In a modified example, the heating request is transmitted to the control device 100 when the heating set temperature is changed. The trigger for the heating request is not particularly limited. If the control device 100 acquires a heating request, the process proceeds to S12 (YES in S10), and if the control device 100 does not acquire a heating request, the process continues at S10 (NO in S10).

[0043] In S12, the control device 100 determines whether the temperature Ts detected by the coolant temperature sensor 24 is less than a predetermined first threshold value Tth1. If the temperature Ts detected by the coolant temperature sensor 24 is less than the first threshold value Tth1 (YES in S12), the process proceeds to S14, and if the temperature Ts is equal to or greater than the first threshold value Tth1 (NO in S12), the process proceeds to S18.

[0044] In S14, the control device 100 determines whether the temperature Tt detected by the converter temperature sensor 22 is less than a predetermined second threshold value Tth2. If the temperature Tt detected by the converter temperature sensor 22 is less than the second threshold value Tth2 (YES in S14), the process proceeds to S16, and if the temperature Tt is equal to or greater than the second threshold value Tth2 (NO in S14), the process proceeds to S18.

[0045] In S16 after YES in S14, the control device 100 executes heat generation control for the converter 20. Specifically, the control device 100 executes hard switching for the primary side circuit 50 of the converter 20. That is, the control device 100 controls the multiple switching elements 51-54 of the primary side circuit 50 by hard switching.

[0046] In hard switching, the control device 100 switches a switching element (e.g., the first switching element 51) of the primary side circuit 50 on and off when the conduction current of the switching element (e.g., the first switching element 51) is not 0 (zero) A. Alternatively, the control device 100 switches a switching element (e.g., the first switching element 51) of the primary side circuit 50 on and off when the applied voltage of the switching element (e.g., the first switching element 51) is not 0 (zero) V.

[0047] In hard switching, for example, the control device 100 makes the difference (t2-t1) between the time t1 at which the first switching element 51 and the fourth switching element 54 of the primary side circuit 50 are turned off and the time t2 at which the second switching element 52 and the third switching element 53 are turned on longer than in soft switching, which will be described later. Also, the control device 100 makes the difference (t4-t3) between the time t3 at which the second switching element 52 and the third switching element 53 of the primary side circuit 50 are turned off and the time t4 at which the first switching element 51 and the fourth switching element 54 are turned on longer than in soft switching. Note that the principle of hard switching is already known, so a detailed description will be omitted.

[0048] In hard switching, switching loss in a switching element (for example, the first switching element 51) is greater than in soft switching. Therefore, in hard switching, a larger amount of heat is generated in a switching element (for example, the first switching element 51) than in soft switching.

[0049] In addition, in the heat generation control of S16, the control device 100 performs diode rectification on the secondary side circuit 60 of the converter 20. In the diode rectification, the control device 100 maintains the multiple switching elements 61-64 of the secondary side circuit 60 of the converter 20 off without synchronizing them with the multiple switching elements 51-54 of the primary side circuit 50. In the diode rectification, no current flows through a transistor (e.g., transistor 61a) of a switching element (e.g., fifth switching element 61) of the secondary side circuit 60, but a current flows through a diode (e.g., diode 61b). This executes diode rectification. Note that the principle of diode rectification is already known, and therefore a detailed description thereof will be omitted.

[0050] In diode rectification, switching loss in a switching element (for example, the fifth switching element 61) is greater than in synchronous rectification, which will be described later. Therefore, in diode rectification, a larger amount of heat is generated in a switching element (for example, the fifth switching element 61) than in synchronous rectification.

[0051] On the other hand, in S18 after NO in S14 above, the control device 100 executes normal control on the converter 20. Specifically, the control device 100 executes soft switching on the primary side circuit 50 of the converter 20. That is, the control device 100 controls the multiple switching elements 51-54 of the primary side circuit 50 by soft switching.

[0052] In soft switching, the control device 100 switches a switching element (e.g., the first switching element 51) of the primary side circuit 50 on and off when the conduction current of the switching element (e.g., the first switching element 51) is 0 (zero) A. Alternatively, the control device 100 switches a switching element (e.g., the first switching element 51) of the primary side circuit 50 on and off when the applied voltage of the switching element (e.g., the first switching element 51) is 0 (zero) V.

[0053] In soft switching, for example, the control device 100 makes the difference (t2-t1) between the time t1 at which the first switching element 51 and the fourth switching element 54 of the primary side circuit 50 are turned off and the time t2 at which the second switching element 52 and the third switching element 53 are turned on shorter than in hard switching. In addition, the control device 100 makes the difference (t4-t3) between the time t3 at which the second switching element 52 and the third switching element 53 of the primary side circuit 50 are turned off and the time t4 at which the first switching element 51 and the fourth switching element 54 are turned on shorter than in hard switching. Note that the principle of soft switching is already known, so a detailed description will be omitted.

[0054] In soft switching, the switching loss in a switching element (for example, the first switching element 51) is smaller than in hard switching.

[0055] In addition, in the normal control of S18, the control device 100 performs synchronous rectification on the secondary side circuit 60 of the converter 20. In the synchronous rectification, the control device 100 controls the multiple switching elements 61-64 of the secondary side circuit 60 of the converter 20 in synchronization with the multiple switching elements 51-54 of the primary side circuit 50. In the synchronous rectification, a current flows through a transistor (e.g., transistor 61a) of a switching element (e.g., fifth switching element 61) of the secondary side circuit 60. This causes synchronous rectification. Note that the principle of synchronous rectification is already known, so a detailed description will be omitted. In the synchronous rectification, the switching loss in a switching element (e.g., fifth switching element 61) is smaller than in diode rectification.

[0056] In the heating process (see FIG. 3), after S16 or S18, the process returns to S12. The heating process ends, for example, when a heating switch (not shown) of the vehicle 4 is turned off.

[0057] In the above-described heating system 2, heat is generated in the multiple switching elements 51-54, 61-64 of the converter 20 by the heat generation control in S18 of the heating process (see FIG. 3). The heat generated in the multiple switching elements 51-54, 61-64 is transferred to the coolant flowing through the coolant flow path 18 of the electronic device 8. The heat transferred from the multiple switching elements 51-54, 61-64 to the coolant is used as heat for heating the interior of the vehicle 4.

[0058] (effect) The heating system 2 of the embodiment has been described above. As described above, the heating system 2 includes a switching element (for example, the first switching element 51) and a coolant flow path 18 that transfers heat generated by the switching element (for example, the first switching element 51) to the coolant. When the control device 100 acquires a heating request while controlling the switching element (for example, the first switching element 51) by soft switching, the control device 100 switches the switching mode of the switching element (for example, the first switching element 51) to control the switching element by hard switching (see FIG. 3).

[0059] According to this configuration, when heat for heating is required, the switching mode of the switching element (for example, the first switching element 51) is switched to hard switching, so that a switching loss occurs in the switching element (for example, the first switching element 51), and the heat generated thereby can be used for heating. By simply switching the switching mode of the switching element (for example, the first switching element 51), heat for heating can be generated by the switching element. By using the heat of the switching element (for example, the first switching element 51), the temperature of the cooling water for heating can be finely adjusted.

[0060] In addition, when the control device 100 acquires a heating request while performing synchronous rectification by periodically switching a switching element (e.g., the fifth switching element 61) on and off, it performs diode rectification by switching the switching method of the switching element (e.g., the fifth switching element 61) and maintaining the switching element (e.g., the fifth switching element 61) off.

[0061] According to this configuration, when heat for heating is needed, the switching mode of a switching element (for example, the fifth switching element 61) is switched to switch the rectification mode to diode rectification, so that a switching loss can be generated in the switching element (for example, the fifth switching element 61), and the heat generated thereby can be used for heating. By simply switching the switching mode of the switching element (for example, the fifth switching element 61), heat for heating can be generated by the switching element.

[0062] The heating system 2 also includes a coolant temperature sensor 24 that detects the temperature of the coolant before it flows into the coolant flow passage 18. When acquiring a heating request, the control device 100 switches the switching mode of the switching elements (for example, the first switching element 51 and the fifth switching element 61) when the temperature Ts detected by the coolant temperature sensor 24 is less than the first threshold value Tth1 (see FIG. 3). With this configuration, for example, when the temperature of the coolant is high, soft switching can be performed, and when the temperature of the coolant is low, hard switching can be performed. Also, when the temperature of the coolant is high, synchronous rectification can be performed, and when the temperature of the coolant is low, diode rectification can be performed. This allows the switching elements (for example, the first switching element 51 and the fifth switching element 61) to generate heat for heating according to the temperature of the coolant.

[0063] The heating system 2 also includes a coolant flow path 16 that transfers heat generated by the engine 6 of the vehicle 4 to the coolant. The coolant temperature sensor 24 detects the temperature of the heat transfer medium before it flows into the coolant flow path 18 of the electronic device 8 and after it flows out of the coolant flow path 16 of the engine 6.

[0064] It is considered that the temperature of the cooling water after the heat generated by the engine 6 is transferred thereto is high. According to this configuration described above, for example, when the temperature of the cooling water after the heat generated by the engine 6 is transferred thereto is high, it is possible to execute soft switching and synchronous rectification. Even if the temperature of the cooling water after the heat generated by the engine 6 is transferred thereto is low, it is possible to execute hard switching and diode rectification. Therefore, heat for heating can be generated by switching elements (for example, the first switching element 51 and the fifth switching element 61) according to the state of heat reception from the engine 6.

[0065] The heating system 2 also includes a converter temperature sensor 22 that detects the temperature of a switching element (e.g., the first switching element 51, the fifth switching element 61) or the temperature of a board (not shown) on which the switching elements are mounted. When acquiring a heating request, the control device 100 switches the switching mode of the switching elements (e.g., the first switching element 51, the fifth switching element 61) if the temperature Tt detected by the converter temperature sensor 22 is less than a second threshold value Tth2.

[0066] According to this configuration, for example, when the temperature of the switching elements (e.g., the first switching element 51, the fifth switching element 61) or the temperature of the board (not shown) on which the switching elements are mounted is high, soft switching and synchronous rectification can be performed. This makes it possible to protect the switching elements (e.g., the first switching element 51, the fifth switching element 61). Also, for example, when the temperature of the switching elements (e.g., the first switching element 51, the fifth switching element 61) or the temperature of the board (not shown) on which the switching elements are mounted is low, hard switching and diode rectification can be performed. This makes it possible to generate heat for heating in the switching elements (e.g., the first switching element 51, the fifth switching element 61).

[0067] Although the embodiment has been described above, the aspect of the heating system 2 is not limited to the above embodiment. In the following description, detailed description of the same configuration as in the above description may be omitted.

[0068] (Modification) (1) In the above embodiment, the converter 20 is an isolated converter in which the primary side circuit 50 and the secondary side circuit 60 are insulated from each other. However, the technology described in this specification is applicable not only to isolated converters but also to non-isolated converters.

[0069] (2) In the above embodiment, the secondary side circuit 60 of the converter 20 includes four switching elements 61-64. However, the present invention is not limited to this configuration. In a modified example, as shown in FIG. 4, the secondary side circuit 60 of the converter 20 may include two switching elements 61-62. The secondary side circuit 60 may also include two secondary side coils 65 (65a, 65b). The fifth switching element 61 may be connected in series with the secondary side coil 65a, and the sixth switching element 62 may be connected in series with the secondary side coil 65b.

[0070] (3) In the above embodiment, the converter 20 has been described, but the technology described in this specification can be applied not only to converters but also to inverters equipped with switching elements. Also, the technology described in this specification can be applied not only to converters and inverters but also to other devices equipped with switching elements.

[0071] (4) In the above embodiment, hard switching and diode rectification are performed in the heat generation control in S16 of the heating process (see FIG. 3), but this is not limited to the above configuration. In a modified example, only one of hard switching and diode rectification may be performed in the heat generation control in S16.

[0072] (5) In the above embodiment, the processes of S12 and S14 are executed in the heating process (see FIG. 3), but the present invention is not limited to this configuration. In a modified example, only one of the processes of S12 and S14 may be executed.

[0073] (6) In the above embodiment, a configuration including the engine 6 has been described, but the present invention is not limited to this configuration. In a modified example, the vehicle 4 and the heating system 2 may not include an engine. The vehicle 4 may be an electric vehicle that does not include an engine. If the vehicle 4 is an electric vehicle, the heating process (see FIG. 3) is started, for example, when the power of the electric vehicle is turned on.

[0074] Furthermore, when the vehicle 4 is an electric vehicle, the vehicle 4 and the heating system 2 may include an electric heater 7 for heating, as shown in Fig. 5. Furthermore, the vehicle 4 and the heating system 2 may not include the second circulation flow path 12, the radiator 36, and the thermostat 32.

[0075] In the heating system 2 shown in Fig. 5, a first circulation flow path 10 circulates the coolant between an electric heater 7, an electronic device 8, and a heater core 38. The electric heater 7 heats the coolant flowing through the first circulation flow path 10. Heat generated by the electric heater 7 is transferred to the coolant.

[0076] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful. [Explanation of symbols]

[0077] 2: heating system, 4: vehicle, 6: engine, 7: electric heater, 8: electronic device, 10: first circulation flow path, 12: second circulation flow path, 16: cooling water flow path, 18: cooling water flow path, 20: converter, 22: converter temperature sensor, 24: cooling water temperature sensor, 30: pump, 32: thermostat, 36: radiator, 36a: cooling water flow path, 38: heater core, 38a: cooling water flow path, 40: power supply, 50: primary side circuit, 51: first switching element, 51a: transistor, 51b: diode, 52: second No. 2 switching element, 53: third switching element, 54: fourth switching element, 55: primary side coil, 56: primary side inductance, 58: primary side capacitor, 60: secondary side circuit, 61: fifth switching element, 61a: transistor, 61b: diode, 62: sixth switching element, 63: seventh switching element, 64: eighth switching element, 65: secondary side coil, 66: secondary side inductance, 68: secondary side capacitor, 70: transformer, 90: secondary battery, 100: control device

Claims

1. A heating system that uses heat generated by a switching element as heat for heating, The switching element; a first heat transfer portion that transfers heat generated by the switching element to a heat medium for heating; A control device that controls a switching operation of the switching element, A heating system, wherein when the control device acquires a specified heating request while controlling the switching element by soft switching, the control device switches a switching mode of the switching element to control the switching element by hard switching.

2. A heating system that uses heat generated by a switching element as heat for heating, The switching element; a first heat transfer portion that transfers heat generated by the switching element to a heat medium for heating; A control device that controls a switching operation of the switching element, A heating system in which, when the control device obtains a specified heating request while performing synchronous rectification by periodically switching the switching element on and off, the control device performs diode rectification by switching the switching method of the switching element and maintaining the switching element off.

3. A heating system according to claim 1 or 2, A first temperature sensor is further provided to detect a temperature of the heat medium before the heat medium flows into the first heat transfer portion. A heating system, wherein, when the control device acquires the heating request, the control device switches a switching mode of the switching element if the temperature detected by the first temperature sensor is lower than a first threshold value.

4. 4. The heating system according to claim 3, which is installed in a vehicle, A second heat transfer unit that transfers heat generated by an engine of the vehicle to a heat medium for heating, A heating system, wherein the first temperature sensor detects a temperature of the heat medium before it flows into the first heat transfer section and after it flows out of the second heat transfer section.

5. A heating system according to claim 1 or 2, a second temperature sensor that detects a temperature of the switching element or a temperature of a substrate on which the switching element is mounted; A heating system, wherein when the control device acquires the heating request, the control device switches the switching mode of the switching element if the temperature detected by the second temperature sensor is lower than a second threshold value.

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