Power supply unit

Abstract

The present invention provides a power supply device, which can appropriately limit the output voltage to an upper limit even if the input voltage of the converter changes, so as to protect the converter from overheating. The power supply device comprises: a converter (20), which converts direct current between an input terminal and an output terminal, and has at least one switching element; and a control circuit (50), which performs switching control on the switching element so that the output voltage (Vout) approaches a target output voltage (Vouto). When the temperature (TC) of the converter exceeds a first judgment value, the control circuit (50) uses a first upper limit value to limit the target output voltage (Vouto), and reduces the first upper limit value as the input voltage (Vin) decreases.

Description

Technical Field

[0001] The present application relates to a power supply device. Background Art

[0002] In a power supply device having a converter that converts direct current between input terminals and output terminals, in order to protect the structural components of the converter from overheating, the upper limit value of the output voltage output from the converter is limited according to the temperature of the converter (for example, the second embodiment of Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 3732828 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] Depending on the input voltage to the converter, even if the output voltage is the same, the converter loss varies. Therefore, even if the upper limit of the output voltage is limited, the converter loss may not be sufficiently reduced depending on the input voltage, and the converter temperature may not be sufficiently reduced. Therefore, in order to reduce the converter loss, improve the converter cooling performance, and improve the converter heat resistance, the weight of the converter increases and the size becomes larger.

[0008] Therefore, an object of the present application is to provide a power supply device that can appropriately limit the upper limit of the output voltage even if the input voltage of the converter changes, so as to protect the converter from overheating.

[0009] Technical solutions adopted to solve technical problems

[0010] The power supply device involved in this application includes:

[0011] a converter, the converter converting direct current between an input terminal and an output terminal, and having at least one switching element;

[0012] a temperature detection circuit, the temperature detection circuit detecting the temperature of the converter;

[0013] An input voltage detection circuit, which detects the voltage of the input terminal, that is, the input voltage;

[0014] an output voltage detection circuit, the output voltage detection circuit detecting the voltage of the output terminal, ie, the output voltage; and

[0015] a control circuit, wherein the control circuit sets a target output voltage and performs switching control on the switch element so that the output voltage approaches the target output voltage,

[0016] The control circuit sets an upper limit on the target output voltage using a first upper limit value when the temperature of the converter exceeds a first determination value.

[0017] As the input voltage decreases, the first upper limit value decreases.

[0018] Effects of the Invention

[0019] According to the power supply device of the present application, when the temperature of the converter exceeds the first judgment value and overheat protection is required, the target output voltage is limited by the first upper limit value, so that the output voltage can be reduced. As the input voltage decreases, the output voltage with the same converter loss decreases. As the input voltage decreases, the first upper limit value decreases, so the converter loss can be appropriately reduced regardless of the input voltage. As a result, the heat generated by the converter can be reduced, the temperature rise of the converter can be suppressed, and overheat protection can be performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a configuration diagram of a power supply device and a rotating electrical machine according to the first embodiment.

[0021] Figure 2 This is a block diagram of a control circuit according to the first embodiment.

[0022] Figure 3 This is a hardware configuration diagram of the control circuit according to the first embodiment.

[0023] Figure 4 This is a timing chart for explaining the PWM control and current operation according to the first embodiment.

[0024] Figure 5 This is a diagram for explaining the reactor loss according to the first embodiment.

[0025] Figure 6 This is a diagram for explaining the switching element loss according to the first embodiment.

[0026] Figure 7 This is a diagram for explaining the motor requested lower limit voltage according to the first embodiment.

[0027] Figure 8 This is a diagram for explaining setting of the first upper limit value according to the first embodiment.

[0028] Fig. 9 This is a timing chart for explaining the control operation according to the first embodiment.

[0029] Fig.10 This is a diagram for explaining the setting of the lower limit value according to the first embodiment.

[0030] Fig.11 It is a structural diagram of a power supply device and a rotating electrical machine according to the second embodiment.

[0031] Fig.12 This is a timing chart for explaining PWM control and current operation when the voltage step-up ratio according to the second embodiment is 2 or more.

[0032] Fig.13 This is a timing chart for explaining PWM control and current operation when the voltage step-up ratio according to the second embodiment is 2 or less.

[0033] Fig.14 This is a diagram for explaining the reactor loss according to the second embodiment.

[0034] Fig.15 This is a diagram for explaining the switching element loss according to the second embodiment.

[0035] Fig.16 This is a timing chart for explaining the first time delay process involved in the third embodiment.

[0036] Fig.17 This is a diagram for explaining the setting of the first upper limit value and the second upper limit value according to the fourth embodiment.

[0037] Fig.18 This is a timing chart for explaining the control operation when the temperature rise according to the fourth embodiment is in a short period of time.

[0038] Fig.19 This is a timing chart for explaining the control operation when the temperature rise according to the fourth embodiment is for a long period of time. DETAILED DESCRIPTION

[0039] 1. Implementation Method 1

[0040] The power supply device according to Embodiment 1 will be described with reference to the drawings. Figure 1 It is a structural diagram of the power supply device involved in this embodiment.

[0041] 1-1. Converter 20

[0042] The converter 20 is a DC-DC converter that converts direct current between an input terminal 1 and an output terminal 2. The converter 20 includes at least one switching element. Furthermore, the converter 20 includes at least one reactor.

[0043] In the present embodiment, the converter 20 is a bidirectional chopper circuit including a step-up chopper circuit that steps up a DC voltage and supplies it from the input terminal 1 to the output terminal 2 , and a step-down chopper circuit that steps down a DC voltage and supplies it from the output terminal 2 to the input terminal 1 .

[0044] The converter 20 includes a positive-side switching element Sa and a negative-side switching element Sb connected in series between a positive-side terminal 2a and a negative-side terminal 2b of the output terminal 2. A reactor L is connected in series between a connection point between the positive-side switching element Sa and the negative-side switching element Sb and a positive-side terminal 1a of the input terminal 1. The negative-side terminal 1b of the input terminal 1 is connected to the negative-side terminal 2b of the output terminal 2.

[0045] Each switching element uses an IGBT (Insulated Gate Bipolar Transistor) with a diode connected in reverse parallel, a FET (Field Effect Transistor) with a diode connected in reverse parallel, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) having the function of a diode connected in reverse parallel, a bipolar transistor with a diode connected in reverse parallel, etc. The gate terminal of each switching element is connected to the control circuit 50. Each switching element is turned on or off according to a control signal output from the control circuit 50.

[0046] An input-side filter capacitor C1 is connected between a positive-side terminal 1a and a negative-side terminal 1b of the input terminal 1. An output-side filter capacitor C2 is connected between a positive-side terminal 2a and a negative-side terminal 2b of the output terminal 2.

[0047] An input voltage detection circuit 3 for detecting the voltage of the input terminal 1, that is, the input voltage Vin, is provided between the positive terminal 1a and the negative terminal 1b of the input terminal 1. The output signal of the input voltage detection circuit 3 is input to the control circuit 50. An output voltage detection circuit 4 for detecting the voltage of the output terminal 2, that is, the output voltage Vout, is provided between the positive terminal 2a and the negative terminal 2b of the output terminal 2. The output signal of the output voltage detection circuit 4 is input to the control circuit 50.

[0048] A temperature detection circuit 5 is provided to detect the temperature of the converter 20. The temperature detection circuit 5 uses a thermistor or the like. The temperature detection circuit 5 is configured to detect the temperature of one or both of the reactor and the switching element. For example, the temperature detection circuit 5 is provided in the reactor or the switching element whose temperature is likely to rise and whose upper limit temperature is relatively low, and whose temperature condition is most stringent. In addition, a plurality of temperature detection circuits 5 may be provided.

[0049] The input terminal 1 is connected to an external DC power source 30 . The output terminal 2 is connected to an external electric load 31 .

[0050] 1-2. Rotating electric machine 40

[0051] In this embodiment, the external electric load 31 is set as a rotating electric machine 40. The rotating electric machine 40 includes an inverter 41 that converts direct current into alternating current and supplies it to a multi-phase (in this example, three phases of U phase, V phase, and W phase) winding, and a rotating electric machine body 42 having a stator and a rotor provided with multi-phase windings. In the inverter 41, three sets of series circuits of switching elements Sma on the positive side and switching elements Smb on the negative side are provided corresponding to each of the three phases. Each switching element is switched by a control circuit 50. The connection point between the two switching elements Sma and Smb of the series circuit of each phase is connected to the winding of the corresponding phase. A winding current detection circuit 43 for detecting the current flowing through the winding of each phase is provided on the connection line of the winding of each phase. In addition, the rotating electric machine body 42 is provided with a rotation detection circuit 44 for detecting the rotation angle of the rotor. The output signals of the winding current detection circuit 43 and the rotation detection circuit 44 are input to the control circuit 50.

[0052] 1-3. Control Circuit 50

[0053] The control circuit 50 controls the converter 20. In this embodiment, the control circuit 50 controls the rotating electric machine in addition to the converter 20. In addition, the rotating electric machine may be controlled by another control circuit. In this case, information on the operating state of the rotating electric machine is input to the control circuit 50 from another control circuit.

[0054] like Figure 2 As shown in FIG. 1 , the control circuit 50 includes a voltage detection unit 51, a temperature detection unit 52, an output voltage control unit 53, and a rotary motor control unit 54, which will be described later. Each function of the control circuit 50 is implemented by a processing circuit provided in the control circuit 50. Specifically, the control device 50 is as follows: Figure 3 As shown, as a processing circuit, it includes an operation processing device 90 (computer) such as a CPU (Central Processing Unit), a storage device 91 for exchanging data with the operation processing device 90, an input circuit 92 for inputting external signals to the operation processing device 90, and an output circuit 93 for outputting signals from the operation processing device 90 to the outside.

[0055] The operation processing device 90 may include an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), various logic circuits, and various signal processing circuits. In addition, the operation processing device 90 may include a plurality of operation processing devices of the same type or different types to share the execution of various processes. The storage device 91 includes a RAM (Random Access Memory) configured to read and write data from the operation processing device 90, a ROM (Read Only Memory) configured to read data from the operation processing device 90, and the like. The input circuit 92 is connected to various sensors such as the input voltage detection circuit 3, the output voltage detection circuit 4, the temperature detection circuit 5, the winding current detection circuit 43, and the rotation detection circuit 44, and includes an A / D converter, etc., which inputs the output signals of these sensors and switches to the operation processing device 90. Output circuit 93 is connected to electric loads such as a gate drive circuit that drives switching elements of converter 20 and rotary electric machine 40 to turn on and off, and includes a drive circuit that outputs control signals from arithmetic processing device 90 to these electric loads.

[0056] The control circuit 50 has Figure 2 Each function of each control unit 51 to 54 is realized by executing the software (program) stored in the storage device 91 such as ROM by the arithmetic processing unit 90, and cooperating with other hardware of the control circuit 50 such as the storage device 91, the input circuit 92 and the output circuit 93. In addition, setting data such as the determination value, upper limit value, release value, basic value of the target output voltage, and motor request lower limit voltage used by each control unit 51 to 54 are stored in the storage device 91 such as ROM as part of the software (program). Hereinafter, each function of the control circuit 50 will be described in detail.

[0057] 1-3-1. Rotating electric machine control unit 54

[0058] The rotating electrical machine control unit 54 detects the rotation angle θ of the rotor, the rotation speed ω, and the winding currents Iu, Iv, and Iw of each phase based on the output signals of the winding current detection circuit 43 and the rotation detection circuit 44. Then, the rotating electrical machine control unit 54 uses a known current vector control method to calculate a voltage command value applied to the winding of each phase based on the rotation angle θ, the rotation speed ω, and the winding currents Iu, Iv, and Iw of each phase so that the rotating electrical machine outputs a target torque, and switches the two switching elements Sma and Smb of each phase using PWM control based on the voltage command value of each phase and the output voltage Vout.

[0059] 1-3-2. Voltage Detection Unit 51

[0060] The voltage detection unit 51 detects the output voltage Vout based on the output signal of the output voltage detection circuit 4 . The voltage detection unit 51 detects the input voltage Vin based on the output signal of the input voltage detection circuit 3 .

[0061] 1-3-3. Temperature Detection Unit 52

[0062] The temperature detection unit 52 detects the converter temperature TC based on the output signal of the temperature detection circuit 5. As the converter temperature TC, the temperature of one or both of the reactor L and the switching element is detected. When a plurality of switching element temperatures are detected, the highest switching element temperature may be selected as the converter temperature TC.

[0063] 1-3-4. Output voltage control unit 53

[0064] In this embodiment, the output voltage control unit 53 includes a target voltage setting unit 531 and a voltage feedback control unit 532 .

[0065] 1-3-4-1. Voltage feedback control unit 532

[0066] The voltage feedback control unit 532 performs switching control on the switching element of the converter 20 so that the output voltage Vout approaches the target output voltage Vouto. The target output voltage Vouto is set by the target voltage setting unit 531 described later. For example, the voltage feedback control unit 532 calculates the voltage control amount Dv that makes the output voltage Vout approach the target output voltage Vouto. For example, the voltage feedback control unit 532 performs PID control on the deviation between the target output voltage Vouto and the output voltage Vout, and calculates the voltage control amount Dv. In addition to PID control, various feedback controls such as PI control can also be used.

[0067] The voltage control amount Dv is set as the duty ratio of the PWM control. The voltage feedback control unit 532 limits the voltage control amount Dv to a range of 0 to 1 (0≤Dv≤1).

[0068] like Figure 4 As shown in the timing diagram, the voltage feedback control unit 532 generates a pulse signal for switching the switching elements on the positive and negative sides of the converter 20 by PWM control based on the voltage control amount Dv (duty cycle). In the present embodiment, the voltage feedback control unit 532 generates a pulse signal Psa for the switching element Sa on the positive side that is turned on according to the voltage control amount Dv (duty cycle) of the converter 20, and inverts the pulse signal Psa of the switching element on the positive side to generate a pulse signal Psb for the switching element Sb on the negative side. Each pulse signal is input to the gate terminal of the corresponding switching element. Although not shown in the figure, there is a dead time (short circuit prevention period) between the conduction period of the switch element Sa on the positive side and the conduction period of the switch element Sb on the negative side, in which both the switch elements on the positive side and the negative side are turned off.

[0069] The applied voltage VL applied to the reactor L becomes the input voltage Vin during the conduction period of the switching element Sa on the positive side, and the reactor current IL flowing through the reactor L increases with the slope of Vin / inductance. On the other hand, the applied voltage VL of the reactor becomes the voltage obtained by subtracting the output voltage Vout from the input voltage Vin during the conduction period of the switching element Sa on the negative side, and the reactor current IL decreases with the slope of (Vin-Vout) / inductance. As the voltage control amount Dv increases, the output voltage Vout increases.

[0070] 1-3-4-2. Target voltage setting unit 531

[0071] <Converter loss corresponding to input voltage and output voltage>

[0072] First, the loss of the switching element (including the diode) which is the largest among the reactor loss and the switching element loss will be described.

[0073] Figure 5 In FIG. 1 , the horizontal axis is the input voltage Vin, the vertical axis is the output voltage Vout, and the characteristics of the reactor loss at each operating point of the input voltage Vin and the output voltage Vout are shown by contour lines. Figure 6 In FIG. 1 , the horizontal axis is the input voltage Vin, the vertical axis is the output voltage Vout, and the characteristics of the switching element loss at each operating point of the input voltage Vin and the output voltage Vout are shown by contour lines.

[0074] The target output voltage Vouto is set to be equal to or higher than the input voltage Vin. Therefore, the region where the output voltage Vout is lower than the input voltage Vin is outside the operating range of the converter, and the reactor loss and the switching element loss are not shown.

[0075] The smaller the input voltage Vin becomes, the smaller the output voltage Vout becomes for the same reactor loss. In addition, the smaller the input voltage Vin becomes, the smaller the output voltage Vout becomes for the same switching element loss. Therefore, in order to reduce the heat generated by the reactor and the heat generated by the switching element, it is necessary to reduce each loss and reduce the output voltage Vout. However, in order to reduce each loss to the same extent, the smaller the input voltage Vin becomes, the smaller the output voltage Vout after the reduction needs to be. It is necessary to reduce the step-up ratio (Vout / Vin) regardless of the change in the input voltage Vin.

[0076] <Motor request lower limit voltage Vmgmin requested by the rotating electrical machine>

[0077] Figure 7 In the figure, the horizontal axis is set to the rotation speed ω of the rotating electrical machine, and the vertical axis is set to the torque T of the rotating electrical machine. At each operating point of the rotation speed ω and the torque T, the characteristics of the minimum required output voltage Vmgmin (hereinafter referred to as the motor requested lower limit voltage Vmgmin) in order to output the desired torque are shown by contour lines. The motor requested lower limit voltage Vmgmin changes according to the torque T and the rotation speed ω of the rotating electrical machine. Specifically, the larger the torque T is and the larger the rotation speed ω is, the larger the motor requested lower limit voltage Vmgmin becomes. This is because the larger the rotation speed ω is, the larger the induced voltage generated in the winding becomes, and in order to output the desired torque, the motor requested lower limit voltage Vmgmin becomes larger, and the larger the output torque T is, the larger the applied voltage of the winding becomes, and in order to output the desired torque, the motor requested lower limit voltage Vmgmin becomes larger. This motor requested lower limit voltage Vmgmin becomes the lower limit value of the target output voltage Vouto.

[0078] Therefore, if setting is possible, the target output voltage Vouto is preferably set to be equal to or higher than the motor request lower limit voltage Vmgmin determined based on the rotation speed ω and the torque T of the rotary electric machine.

[0079] <Upper limit of target output voltage corresponding to converter temperature TC>

[0080] If the voltage step-up ratio (Vout / Vin) of the converter 20 increases, Figure 5 and Figure 6 As shown, the reactor loss and the switching element loss increase, so the heat generated by the components of the converter 20 such as the reactor L and the switching element increases, and the converter temperature TC rises. Overheat protection is required so that the converter temperature TC does not rise above the allowable temperature.

[0081] When the converter temperature TC is low, it is not necessary to reduce the step-up ratio to reduce the heat generated by the components of the converter 20. Therefore, when the converter temperature TC is lower than the first judgment value Vth1, the target voltage setting unit 531 sets the target output voltage Vouto within a range greater than the input voltage Vin. In the present embodiment, the target voltage setting unit 531 sets the target output voltage Vouto within a range greater than the input voltage Vin and greater than the motor request lower limit voltage Vmgmin determined based on the rotation speed ω and torque T of the rotating electrical machine. For example, the target voltage setting unit 531 sets the target output voltage Vouto to an output voltage Vout in which the loss of the converter 20 and the loss of the rotating electrical machine 40 (the inverter 41 and the rotating electrical machine body 42) are reduced within the settable range of the target output voltage Vouto.

[0082] For example, the target voltage setting unit 531 refers to a basic value setting map that predefines the relationship between the input voltage Vin and the basic value Voutob of the target output voltage, and calculates the basic value Voutob of the target output voltage corresponding to the current input voltage Vin. Figure 7 The motor lower limit voltage Vmgmin corresponding to the current rotating electrical machine rotation speed ω and target torque To is calculated using the rotating electrical machine lower limit voltage map in which the relationship between the rotating electrical machine rotation speed ω, torque T and motor request lower limit voltage Vmgmin is preset as shown.

[0083] Then, the target voltage setting unit 531 uses the motor request lower limit voltage Vmgmin of the rotary electric machine to set a lower limit on the basic value Voutob of the target output voltage, and calculates the value obtained as the target output voltage Vouto. The basic value Voutob of the target output voltage of the basic value setting map is pre-set to an output voltage Vout that is higher than the input voltage Vin and at which each loss is reduced at the operating point of each input voltage Vin.

[0084] However, when the converter temperature TC becomes high and overheat protection is required, in order to reduce the step-up ratio and reduce the heat generation, it is necessary to set an upper limit on the target output voltage Vouto. Therefore, when the converter temperature TC exceeds the first judgment value Vth1, the target voltage setting unit 531 sets an upper limit on the target output voltage Vouto using the first upper limit value Vup1. Figure 8 As shown in FIG. 1 , the target voltage setting unit 531 decreases the first upper limit value Vup1 as the input voltage Vin decreases. In addition, the first upper limit value Vup1 is set to a value greater than or equal to the input voltage Vin.

[0085] According to this structure, when the temperature TC of the converter exceeds the first judgment value Vth1 and overheat protection is required, the first upper limit value Vup1 can be used to set an upper limit on the target output voltage Vouto. As the input voltage Vin decreases, the output voltage Vout with the same reactor loss and switching element loss decreases. As the input voltage Vin decreases, the first upper limit value Vup1 decreases, so the reactor loss and switching element loss can be appropriately reduced regardless of the input voltage Vin. As a result, the heat generation of the reactor and the switching element can be reduced, the temperature rise of the converter can be suppressed, and overheat protection can be performed.

[0086] The first determination value Vth1 is preset based on the converter temperature TC at which overheat protection is required. The first upper limit value Vup1 is preset to a value at which the converter temperature TC drops below the allowable temperature at the operating point of each input voltage Vin. The target voltage setting unit 531 calculates the first upper limit value Vup1 corresponding to the current input voltage Vin by referring to the first upper limit value setting map in which the relationship between the input voltage Vin and the first upper limit value Vup1 is preset.

[0087] The target voltage setting unit 531 uses the first upper limit value Vup1 to limit the target output voltage Vouto calculated when the converter temperature TC is less than the first determination value Vth1. For example, the target voltage setting unit 531 refers to the basic value setting map in which the relationship between the input voltage Vin and the basic value Voutob of the target output voltage is preset, and calculates the basic value Voutob of the target output voltage corresponding to the current input voltage Vin. Then, the target voltage setting unit 531 limits the basic value Voutob of the target output voltage to the lower limit by using the motor request lower limit voltage Vmgmin of the rotary electric machine, and calculates the value obtained by limiting the value obtained by using the first upper limit value Vup1 as the target output voltage Vouto.

[0088] Here, the process of upper-limiting A with B is equivalent to the process of outputting the smaller value of A and B. In addition, the process of lower-limiting A with B is equivalent to the process of outputting the larger value of A and B.

[0089] In the present embodiment, after the converter temperature TC exceeds the first determination value Vth1 and the converter temperature TC becomes lower than the first release value Vst1, the target voltage setting unit 531 terminates the upper limit restriction process of the target output voltage Vouto based on the first upper limit value Vup1. The first release value Vst1 is set in advance to a value less than the first determination value Vth1. For example, the first release value Vst1 is set to a value that is about 10 degrees smaller than the first determination value Vth1 so that the start and end of the upper limit restriction process are not repeated in a short period of time.

[0090] <Control Action>

[0091] Fig. 9 An example of the control action is shown in FIG. Before time t01, the target voltage setting unit 531 determines that the converter temperature TC is lower than the first determination value Vth1, and sets the target output voltage Vouto without performing the upper limit restriction process of the target output voltage Vouto based on the first upper limit value Vup1. In the present embodiment, the target voltage setting unit 531 calculates the basic value Voutob of the target output voltage in which each loss becomes low within the range of the input voltage Vin and the motor request lower limit voltage Vmgmin, and directly sets the basic value Voutob of the target output voltage as the target output voltage Vouto.

[0092] At time t01, due to some reasons, an abnormality occurs in which the temperature of the cooling water for cooling the converter 20 rises excessively. After that, the converter temperature TC gradually rises, and at time t02, the target voltage setting unit 531 determines that the converter temperature TC is higher than the first determination value Vth1, and starts the upper limit restriction process of the target output voltage Vouto based on the first upper limit value Vup1. In this embodiment, similar to the case where the upper limit restriction process of the target output voltage Vouto is not performed, the target voltage setting unit 531 calculates the basic value Voutob of the target output voltage, performs upper limit restriction on the basic value Voutob of the target output voltage using the first upper limit value Vup1, and sets the value obtained as the target output voltage Vouto. Fig. 9 In the example of , the basic value Voutob of the target output voltage exceeds the first upper limit value Vup1 , and the first upper limit value Vup1 is set as the target output voltage Vouto.

[0093] Thereafter, due to the reduction in the output voltage, the loss and heat generation of the converter are reduced, and the converter temperature TC can be made lower than the first determination value Vth1, so that the overheat protection of the converter can be performed.

[0094] At time t03, the abnormality of excessive increase in the temperature of the cooling water is eliminated. After time t03, the converter temperature TC gradually decreases. At time t04, the converter temperature TC is lower than the first release value Vst1, so the target voltage setting unit 531 ends the upper limit restriction process of the target output voltage Vouto based on the first upper limit value Vup1, and directly sets the basic value Voutob of the target output voltage as the target output voltage Vouto.

[0095] <Lower limit value of target output voltage>

[0096] In the above, the case where the target output voltage Vouto (the basic value Voutob of the target output voltage) is set to a value greater than the input voltage Vin is described as an example. However, when the output voltage Vout is close to the input voltage Vin, if there is a transient change in the current flowing through the converter 20 or in the input voltage Vin, the control of the output voltage Vout may become unstable. Fig.10 As shown, the target voltage setting unit 531 can use the lower limit value Vmin to set the lower limit of the target output voltage Vouto, and the above lower limit value Vmin is obtained by adding a pre-set positive offset value to the input voltage Vin. That is, the target output voltage Vouto (the basic value Voutob of the target output voltage) can also be set to a value greater than the lower limit value Vmin. The first upper limit value Vup1 is set to a value greater than the lower limit value Vmin.

[0097] 2. Implementation Method 2

[0098] A power supply device according to Embodiment 2 will be described. Description of the same components as those of Embodiment 1 will be omitted. The basic structure of the power supply device according to this embodiment is the same as that of Embodiment 1, but the structure of converter 20 is different from that of Embodiment 1. Fig.11 It is a configuration diagram of the converter 20 according to the present embodiment.

[0099] In this embodiment, the converter 20 includes a first switching element S1, a second switching element S2, a third switching element S3, and a fourth switching element S4 connected in series from the positive side between the positive side terminal 2a and the negative side terminal 2b of the output terminal 2. The gate terminal of each switching element is connected to the control circuit 50. Each switching element is turned on or off according to a control signal output from the control circuit 50.

[0100] A reactor L is connected in series between a connection point between the second switching element S2 and the third switching element S3 and the positive electrode side terminal 1 a of the input terminal 1 .

[0101] A charging and discharging capacitor C3 is connected between a connection point between the first switching element S1 and the second switching element S2 and a connection point between the third switching element S3 and the fourth switching element S4. An intermediate voltage detection circuit 6 is provided for detecting an intermediate voltage Vmid, which is a voltage between the terminals of the charging and discharging capacitor C3. An output signal of the intermediate voltage detection circuit 6 is input to a control circuit 50.

[0102] Similar to the first embodiment, a filter capacitor C1 on the input side is connected between the positive terminal 1a and the negative terminal 1b of the input terminal 1. A filter capacitor C2 on the output side is connected between the positive terminal 2a and the negative terminal 2b of the output terminal 2. An input voltage detection circuit 3 for detecting the voltage of the input terminal 1, i.e., the input voltage Vin, is provided between the positive terminal 1a and the negative terminal 1b of the input terminal 1. An output voltage detection circuit 4 for detecting the voltage of the output terminal 2, i.e., the output voltage Vout, is provided between the positive terminal 2a and the negative terminal 2b of the output terminal 2.

[0103] In the present embodiment, the voltage detection unit 51 detects the intermediate voltage Vmid based on the output signal of the intermediate voltage detection circuit 6 .

[0104] The voltage feedback control unit 532 performs switching control on the switching element of the converter 20 so that the output voltage Vout approaches the target output voltage Vouto. For example, the voltage feedback control unit 532 calculates the voltage control amount Dv that makes the output voltage Vout approach the target output voltage Vouto. In this embodiment, the voltage feedback control unit 532 calculates the intermediate voltage control amount Dmid that makes the intermediate voltage Vmid approach half the value (Vouto / 2) of the target output voltage Vouto. Then, as Fig.12 , Fig.13 As shown, the voltage feedback control unit 532 generates pulse signals Ps1, Ps2, Ps3, Ps4 for switching the first, second, third, and fourth switching elements S1, S2, S3, S4, respectively, based on the voltage control amount Dv and the intermediate voltage control amount Dmid. The generation of the pulse signal uses a known method disclosed in International Publication No. 2012 / 014912, etc.

[0105] Fig.12 and Fig.13 The timing diagram shows the switching action of the switching element. Fig.12 This is the case when the boost ratio is greater than 2. Fig.13 This is the case where the voltage step-up ratio is greater than 1 and less than 2.

[0106] The pulse signal Ps1 of the first switching element and the pulse signal Ps4 of the fourth switching element become inverted signals. Although not shown in the figure, a dead time (short-circuit prevention period) is provided between the on-time of the first switching element and the on-time of the fourth switching element. The pulse signal Ps2 of the second switching element and the pulse signal Ps3 of the third switching element become inverted signals. Although not shown in the figure, a dead time (short-circuit prevention period) is provided between the on-time of the second switching element and the on-time of the third switching element. A phase difference is provided between the pulse signals Ps1 and Ps4 of the first and fourth switching elements and the pulse signals Ps2 and Ps3 of the second and third switching elements.

[0107] For a step-up ratio of 2 or more Fig.12 For explanation. When the pulse signal Ps3 of the third switching element and the pulse signal Ps4 of the fourth switching element are both turned on, the applied voltage VL applied to the reactor L becomes the input voltage Vin, and the reactor current IL increases at a slope of Vin / inductance. On the other hand, when the pulse signal Ps2 of the second switching element and the pulse signal Ps4 of the fourth switching element are both turned on, and when the pulse signal Ps1 of the first switching element and the pulse signal Ps3 of the third switching element are both turned on, the applied voltage VL of the reactor becomes Vin-Vout / 2, and the reactor current IL decreases at a slope of (Vin-Vout / 2) / inductance.

[0108] For a step-up ratio of 1 or more and 2 or less Fig.13 For explanation. When both the pulse signal Ps2 of the second switching element and the pulse signal Ps4 of the fourth switching element are turned on, and when both the pulse signal Ps1 of the first switching element and the pulse signal Ps3 of the third switching element are turned on, the applied voltage VL of the reactor L becomes Vin-Vout / 2, and the reactor current IL increases at a slope of (Vin-Vout / 2) / inductance. On the other hand, when both the pulse signal Ps1 of the first switching element and the pulse signal Ps2 of the second switching element are turned on, the applied voltage VL of the reactor becomes Vin-Vout, and the reactor current IL decreases at a slope of (Vin-Vout) / inductance.

[0109] Fig.14 In FIG. 1 , the horizontal axis is the input voltage Vin, the vertical axis is the output voltage Vout, and the characteristics of the reactor loss at each operating point of the input voltage Vin and the output voltage Vout are shown by contour lines. Fig.15 In FIG. 1 , the horizontal axis is the input voltage Vin, the vertical axis is the output voltage Vout, and the characteristics of the switching element loss at each operating point of the input voltage Vin and the output voltage Vout are shown by contour lines.

[0110] The target output voltage Vouto is set to be equal to or higher than the input voltage Vin. Therefore, the region where the output voltage Vout is lower than the input voltage Vin is outside the operating range of the converter, and the reactor loss and the switching element loss are not shown.

[0111] When the boost ratio (Vout / Vin) is near 1, the reactor loss and the switching element loss become smaller, and the loss increases as the boost ratio approaches 1 to 1.3. In addition, the loss decreases as the boost ratio approaches 1.3 to 2, and the loss increases again as the boost ratio increases from 2.

[0112] As mentioned above, in order to reduce the heat generated by the reactor and the switching element, it is necessary to reduce each loss. In order to reduce each loss, it is necessary to change the step-up ratio to around 1.3 (or around 2). For this reason, the smaller the input voltage Vin, the smaller the output voltage after the step-down needs to be.

[0113] As in the first embodiment, when the converter temperature TC is lower than the first determination value Vth1, the target voltage setting unit 531 sets the target output voltage Vouto within a range greater than the input voltage Vin. In addition, the target voltage setting unit 531 sets the target output voltage Vouto within a range greater than the input voltage Vin and greater than the motor request lower limit voltage Vmgmin determined based on the rotation speed and torque of the rotary electric machine. For example, the target voltage setting unit 531 sets the target output voltage Vouto to an output voltage Vout in which the loss of the converter 20 and the loss of the rotary electric machine 40 (the inverter 41 and the rotary electric machine body 42) are reduced within the settable range of the target output voltage Vouto.

[0114] As in the first embodiment, when the converter temperature TC exceeds the first determination value Vth1, the target voltage setting unit 531 sets an upper limit on the target output voltage Vouto using the first upper limit value Vup1. Figure 8 As shown, target voltage setting unit 531 decreases first upper limit value Vup1 as input voltage Vin decreases. Target voltage setting unit 531 uses first upper limit value Vup1 to set an upper limit on target output voltage Vouto calculated when converter temperature TC is lower than first determination value Vth1.

[0115] Furthermore, after converter temperature TC exceeds first determination value Vth1 and converter temperature TC becomes lower than first release value Vst1, target voltage setting unit 531 terminates the upper limit restriction process of target output voltage Vouto based on first upper limit value Vup1. Target voltage setting unit 531 may lower limit target output voltage Vouto using lower limit value Vmin obtained by adding a preset positive offset value to input voltage Vin.

[0116] 3. Implementation Method 3

[0117] The power supply device according to Embodiment 3 will be described. The description of the same components as those in Embodiment 1 or 2 will be omitted. The basic structure of the power supply device according to this embodiment is the same as that in Embodiment 1 or 2, but the processing of the target voltage setting unit 531 is different from that in Embodiment 1 or 2.

[0118] <First time delay processing>

[0119] like Fig.16 As shown in FIG. 1 , the following case is described: when the upper limit restriction process of the target output voltage Vouto based on the first upper limit value Vup1 is performed, the input voltage Vin changes rapidly. Figure 8 As shown, the first upper limit value Vup1 also changes in accordance with the rapid change in the input voltage Vin, and the target output voltage Vouto which is upper-limited by the first upper limit value Vup1 also changes rapidly.

[0120] If the target output voltage Vouto changes suddenly, the output voltage Vout changes suddenly, and the operation of the converter 20 and the operation of the electric load 31 (in this example, the rotating electric machine 40 ) may become unstable.

[0121] Therefore, in the present embodiment, the target voltage setting unit 531 sets the first upper limit value Vup1 based on the value obtained by performing the first time delay processing on the input voltage Vin. According to this structure, even if the input voltage Vin changes suddenly, the sudden change of the first upper limit value Vup1 can be suppressed, and the sudden change of the output voltage Vout can be suppressed. In addition, similarly to the first embodiment, the target voltage setting unit 531 sets the first upper limit value Vup1 based on the input voltage Vin, and uses the value obtained by performing the first time delay processing on the first upper limit value Vup1 as the final first upper limit value Vup1.

[0122] For example, the first time delay process is set as a low-pass filter process such as a first-order delay process. The thermal time constants of the components of the converter are set so that the time delay of the change of the converter temperature TC is greater than the time delay of the first time delay process. According to this configuration, the change of the converter temperature TC caused by the rapid change component of the input voltage Vin and the output voltage Vout reduced by the first time delay process becomes smaller. Therefore, even if the first time delay process is performed, the performance of suppressing the increase of the converter temperature TC can be maintained.

[0123] The characteristics of the change in converter temperature TC are determined by the thermal capacity of each component of the converter and the cooling system, etc. For example, the thermal time constant (heat capacity) of the components of the converter, such as the reactor and the switching element, is set so that the time constant of the change in converter temperature TC with respect to the step change in the boost ratio is greater than the time constant of the first time delay process.

[0124] Alternatively, the time constant of the first time delay process may be set so that the time delay of the first time delay process is smaller than the time delay of the change in converter temperature TC.

[0125] <Second time delay processing>

[0126] The target voltage setting unit 531 sets the target output voltage before the upper limit (the basic value Voutob of the target output voltage) based on the operating state of the external electrical load 31 (in this example, the speed and torque of the rotating motor 40), and performs a second time delay processing on the operating state of the external electrical load or the target output voltage before the upper limit.

[0127] In this embodiment, the target voltage setting unit 531 calculates the motor request lower limit voltage Vmgmin of the rotating electrical machine based on the rotation speed ω and torque T of the rotating electrical machine, and uses the motor request lower limit voltage Vmgmin to lower-limit the basic value Voutob of the target output voltage. The target voltage setting unit 531 performs a second time delay process on the basic value Voutob of the target output voltage that is lower-limited by the rotation speed ω and torque T of the rotating electrical machine or the motor request lower limit voltage Vmgmin.

[0128] According to this configuration, when the target output voltage Vouto is not limited by the first upper limit value Vup1 but is set to a value limited by the motor request lower limit voltage Vmgmin, it is possible to suppress a sudden change in the target output voltage Vouto due to a sudden change in the operating state of the external electric load 31 (the speed and torque of the rotating electric machine 40), and to suppress a sudden change in the output voltage Vout. As a result, it is possible to suppress the operation of the converter 20 and the operation of the electric load 31 (rotating electric machine 40) from becoming unstable.

[0129] The time delay of the first time delay process is greater than the time delay of the second time delay process. For example, the time constant of the first time delay process is set to be greater than the time constant of the second time delay process. The time delay of the second time delay process is set so that even if the target output voltage Vouto changes according to the rotation speed and torque changes of the rotating electric machine 40, the operation of the converter 20 and the operation of the electric load 31 (rotating electric machine 40) will not become unstable. Therefore, the time delay of the first time delay process is greater than the time delay of the second time delay process, and therefore, the change speed of the target output voltage Vouto relative to the change of the input voltage Vin is greater than the change speed of the target output voltage Vouto relative to the change of the rotation speed and torque of the rotating electric machine 40. Therefore, even if the target output voltage Vouto changes according to the change of the input voltage Vin, it is possible to operate on the safe side so that the operation of the converter 20 and the operation of the electric load 31 (rotating electric machine 40) will not become unstable.

[0130] 4. Implementation Method 4

[0131] The power supply device involved in Embodiment 4 is described. The description of the same structural parts as those in Embodiment 1 or 2 is omitted. The basic structure of the power supply device involved in this embodiment is the same as that in Embodiment 1 or 2, but the structure of the temperature detection circuit 5 and the processing of the target voltage setting unit 531 are different from those in Embodiment 1 or 2.

[0132] In the present embodiment, a first temperature detection circuit for detecting the reactor temperature TL and a second temperature detection circuit for detecting the switching element temperature TS are provided as the temperature detection circuit 5 .

[0133] The temperature detection unit 52 detects the reactor temperature TL based on the output signal of the first temperature detection circuit, and detects the switching element temperature TS based on the output signal of the second temperature detection circuit.

[0134] In the present embodiment, the thermal time constant of the reactor is greater than that of the switching element. Therefore, in response to abnormality in the cooling system, an increase in the voltage step-up ratio, etc., the switching element temperature TS rises before the reactor temperature TL.

[0135] For example, the heat capacity of the reactor is increased by increasing the specific heat and mass of the structural members of the reactor, thereby making the thermal time constant of the reactor larger than the thermal time constant of the switching element.

[0136] In this embodiment, the target voltage setting unit 531 sets an upper limit on the target output voltage Vouto using the second upper limit value Vup2 when the reactor temperature TL does not exceed the first judgment value Vth1 and the switching element temperature TS exceeds the second judgment value Vth2. Fig.17As shown, the second upper limit value Vup2 is larger than the first upper limit value Vup1 and does not change according to the input voltage Vin.

[0137] When the reactor temperature TL exceeds the first determination value Vth1 , the target voltage setting unit 531 imposes an upper limit on the target output voltage Vouto using the first upper limit value Vup1 .

[0138] According to this structure, when the temperature TS of the switching element with a relatively fast temperature rise rate exceeds the second judgment value Vth2, the target output voltage Vouto is limited by the second upper limit value Vup2, thereby reducing the heat generated by the switching element and suppressing the rise of the switching element temperature TS. The second judgment value Vth2 is preset based on the temperature of the switching element that needs to be overheated protected. The second upper limit value Vup2 is set to the output voltage Vout to a degree that can suppress the temperature rise of the switching element.

[0139] When the temperature rise of the reactor cannot be suppressed even when the upper limit processing of the target output voltage Vouto based on the second upper limit value Vup2 is performed, the reactor temperature TL increases relatively slowly. When the reactor temperature TL exceeds the first judgment value Vth1, the target output voltage Vouto is upper-limited by the first upper limit value Vup1 which is smaller than the second upper limit value Vup2, thereby further reducing the heat generation of the reactor and the switching element and suppressing the rise of the reactor temperature TL. The first judgment value Vth1 is pre-set based on the temperature of the reactor that needs to be overheated protected. The first upper limit value Vup1 is set to the output voltage Vout to a degree that can suppress the temperature rise of the reactor.

[0140] As in the first embodiment, the target voltage setting unit 531 calculates the basic value Voutob of the target output voltage within the range above the input voltage Vin. For example, the target voltage setting unit 531 calculates the basic value Voutob of the target output voltage in which each loss becomes low within the range above the input voltage Vin and above the motor request lower limit voltage Vmgmin. Then, the target voltage setting unit 531 directly sets the basic value Voutob of the target output voltage as the target output voltage Vouto without performing the upper limit processing of the target output voltage Vouto based on the first upper limit value Vup1 or the second upper limit value Vup2.

[0141] When the target voltage setting unit 531 performs the upper limit restriction processing of the target output voltage Vouto based on the first upper limit value Vup1, the target voltage setting unit 531 performs the upper limit restriction on the basic value Voutob of the target output voltage using the first upper limit value Vup1, and sets the value obtained thereby as the target output voltage Vouto. When the target voltage setting unit 531 performs the upper limit restriction processing of the target output voltage Vouto based on the second upper limit value Vup2, the target voltage setting unit 531 performs the upper limit restriction on the basic value Voutob of the target output voltage using the second upper limit value Vup2, and sets the value obtained thereby as the target output voltage Vouto.

[0142] <Control Action>

[0143] Fig.18 and Fig.19 An example of a control action is shown in FIG. Fig.18 The example is when the cause of the temperature rise occurs in a short period of time. Fig.19 An example is when the cause of the temperature rise occurs over a long period of time.

[0144] First of all, Fig.18 Before time t11, the target voltage setting unit 531 determines that the reactor temperature TL is lower than the first determination value Vth1, and determines that the switching element temperature TS is lower than the second determination value Vth2, and does not perform upper limit processing on the target output voltage Vouto based on the first upper limit value Vup1 and the second upper limit value Vup2, and directly sets the basic value Voutob of the target output voltage as the target output voltage Vouto.

[0145] At time t11, due to some reasons, an abnormality occurs in which the temperature of the cooling water for cooling the converter 20 rises excessively. After that, the switching element temperature TS rises rapidly. At time t12, the target voltage setting unit 531 determines that the switching element temperature TS is higher than the second determination value Vth2, and starts the upper limit restriction process of the target output voltage Vouto based on the second upper limit value Vup2. The target voltage setting unit 531 uses the second upper limit value Vup2 to impose an upper limit on the basic value Voutob of the target output voltage, and sets the value obtained as the target output voltage Vouto. On the other hand, the thermal time constant of the reactor is larger than the thermal time constant of the switching element, so the reactor temperature TL increases relatively slowly, and the reactor temperature TL does not exceed the first determination value Vth1.

[0146] Thereafter, due to the reduction in the output voltage, the loss and heat generation of the converter are reduced, and the switching element temperature TS can be made lower than the second determination value Vth2, so that the switching element can be protected from overheating.

[0147] At time t13, the abnormality of excessive temperature rise of cooling water is eliminated. After time t13, the switching element temperature TS decreases relatively quickly. At time t14, the switching element temperature TS is lower than the second release value Vst2, so the target voltage setting unit 531 ends the upper limit restriction process of the target output voltage Vouto based on the second upper limit value Vup2, and directly sets the basic value Voutob of the target output voltage as the target output voltage Vouto. The second release value Vst2 is set to be less than the second upper limit value Vup2.

[0148] Thus, when the cause of the temperature rise occurs in a short period of time, the rise of the reactor temperature TL having a large thermal time constant is relatively small, and the rise of the switching element temperature TS having a small thermal time constant is relatively large. Then, in order to reduce the switching element temperature TS, the target output voltage Vouto is reduced to the second upper limit value Vup2 which is larger than the first upper limit value Vup1, so that the decrease amount of the target output voltage Vouto can be suppressed to the necessary minimum.

[0149] Next, Fig.19 Before time t21, the target voltage setting unit 531 determines that the reactor temperature TL is lower than the first determination value Vth1, and determines that the switching element temperature TS is lower than the second determination value Vth2, and does not perform upper limit processing on the target output voltage Vouto based on the first upper limit value Vup1 and the second upper limit value Vup2, and directly sets the basic value Voutob of the target output voltage as the target output voltage Vouto.

[0150] At time t21, due to some reasons, an abnormality occurs in which the temperature of the cooling water for cooling the converter 20 rises excessively. After that, the switching element temperature TS rises relatively quickly. At time t22, the target voltage setting unit 531 determines that the switching element temperature TS is higher than the second determination value Vth2, and starts the upper limit restriction process of the target output voltage Vouto based on the second upper limit value Vup2. The target voltage setting unit 531 uses the second upper limit value Vup2 to impose an upper limit on the basic value Voutob of the target output voltage, and sets the value obtained as the target output voltage Vouto.

[0151] Thereafter, due to the reduction in the output voltage, the loss and heat generation of the converter are reduced, and the switching element temperature TS can be made lower than the second determination value Vth2, so that the switching element can be protected from overheating.

[0152] On the other hand, the upper limit restriction process of the target output voltage Vouto based on the second upper limit value Vup2 alone is not sufficient to suppress the increase in the reactor temperature TL. Therefore, after time 22, the reactor temperature TL having a large thermal time constant also increases relatively slowly.

[0153] Then, at time 23, the target voltage setting unit 531 determines that the reactor temperature TL is higher than the first determination value Vth1, and starts the upper limit restriction process of the target output voltage Vouto based on the first upper limit value Vup1. The target voltage setting unit 531 uses the first upper limit value Vup1 to impose an upper limit restriction on the basic value Voutob of the target output voltage, and sets the value obtained as the target output voltage Vouto. Since the output voltage is further reduced, the loss and heat generation of the converter are further reduced, and the reactor temperature TL can be made lower than the first determination value Vth1, and the overheat protection of the reactor can be performed.

[0154] Although not in Fig.19 However, if the abnormality is subsequently eliminated and the reactor temperature TL falls below the first release value Vst1, the target voltage setting unit 531 ends the upper limit restriction process of the target output voltage Vouto based on the first upper limit value Vup1. The first release value Vst1 is set to be equal to or less than the first upper limit value Vup1.

[0155] In this way, when the cause of the temperature rise occurs over a long period of time, the rise of the reactor temperature TL having a large thermal time constant also becomes larger. In order to reduce the reactor temperature TL, the target output voltage Vouto is reduced to the first upper limit value Vup1 which is smaller than the second upper limit value Vup2. Therefore, the reduction amount of the target output voltage Vouto can be increased, the reactor temperature TL can be reduced, and the overheat protection of the reactor can be performed.

[0156] [Other embodiments]

[0157] (1) In the above-mentioned Embodiment 1, the converter 20 is a bidirectional chopper circuit having two switching elements connected in series, and in Embodiment 2, the converter 20 is a bidirectional chopper circuit having four switching elements connected in series, and this case is used as an example for explanation. However, as long as the converter 20 is a DC-DC converter that converts direct current between the input terminal 1 and the output terminal 2 and has an inductor and a switching element, it can also be another type of converter. For example, the converter 20 can be a boost chopper circuit that boosts the direct current voltage and provides it from the input terminal 1 to the output terminal 2. In this case, the switching element on the positive side in Embodiment 1 can be a diode. Alternatively, the converter 20 can be a buck chopper circuit that steps down the direct current voltage and provides it from the output terminal 2 to the input terminal 1. In this case, the switching element on the negative side in Embodiment 1 can be a diode. Alternatively, the converter 20 can be a transformer-insulated type.

[0158] (2) In the above embodiments, the external electric load 31 is described as the rotating electric machine 40. However, the external electric load 31 may be any electric load other than the rotating electric machine 40, or may be a plurality of rotating electric machines 40 connected in parallel.

[0159] Although the present application describes various exemplary embodiments and examples, the various features, modes and functions described in one or more embodiments are not limited to the application of specific embodiments and can be applied to the embodiments individually or in various combinations. Therefore, it can be considered that countless variations that are not illustrated are also included in the technical scope disclosed in the present application specification. For example, it is assumed that at least one constituent element is deformed, added or omitted, and at least one constituent element is extracted and combined with constituent elements of other embodiments.

[0160] Description of symbols

[0161] 1 Input terminal

[0162] 2 Output terminals

[0163] 3 Input voltage detection circuit

[0164] 4 Output voltage detection circuit

[0165] 5 Temperature Detection Circuit

[0166] 20 Converter

[0167] 30 DC power supply

[0168] 31 External electrical load

[0169] 40 Rotating motor

[0170] 50 Control circuit

[0171] 51 Voltage detection unit

[0172] 52. Temperature detection unit

[0173] 53 Output voltage control unit

[0174] L Reactor

[0175] TC Converter Temperature

[0176] TL Reactor temperature

[0177] TS Switching element temperature

[0178] Vin Input voltage

[0179] Vout Output voltage

[0180] Vouto target output voltage

[0181] Vth1 1st judgment value

[0182] Vth2 Second judgment value

[0183] Vup1 1st upper limit value

[0184] Vup2 Second upper limit value.

Claims

1. A power supply device, characterized in that: include: a converter, the converter converting direct current between an input terminal and an output terminal, and having at least one switching element; a temperature detection circuit, the temperature detection circuit detecting the temperature of the converter; An input voltage detection circuit, which detects the voltage of the input terminal, that is, the input voltage; an output voltage detection circuit, wherein the output voltage detection circuit detects the voltage of the output terminal, that is, the output voltage; as well as a control circuit, wherein the control circuit sets a target output voltage and performs switching control on the switch element so that the output voltage approaches the target output voltage, The control circuit sets an upper limit on the target output voltage using a first upper limit value when the temperature of the converter exceeds a first determination value. As the input voltage decreases, the first upper limit value decreases. The control circuit sets a lower limit on the target output voltage using a lower limit value obtained by adding a preset positive offset value to the input voltage.

2. The power supply device according to claim 1, characterized in that: The control circuit sets the first upper limit value based on a value obtained by performing a first time delay process on the input voltage. The thermal time constant of the components of the converter is set so that the time delay of the temperature change of the converter is greater than the time delay of the first time delay process.

3. The power supply device according to claim 2, characterized in that: The control circuit sets the target output voltage before upper limit limitation based on the operating state of the external electric load connected to the output terminal, and performs a second time delay process on the operating state of the external electric load or the target output voltage before upper limit limitation. The time delay of the first time delay process is greater than the time delay of the second time delay process.

4. The power supply device according to claim 3, characterized in that: The external electrical load is a rotating electrical machine, The control circuit uses the rotation speed and torque of the rotating electric machine as the operating state of the external electric load.

5. The power supply device according to any one of claims 1 to 4, characterized in that: The converter has at least one reactor, The temperature detection circuit detects the temperature of the switching element and the temperature of the reactor as the temperature of the converter, When the temperature of the reactor does not exceed the first judgment value and the temperature of the switching element exceeds the second judgment value, the target output voltage is limited by a second upper limit value that is larger than the first upper limit value and does not vary according to the input voltage. When the temperature of the reactor exceeds the first determination value, the target output voltage is limited to an upper limit using a first upper limit value, The thermal time constant of the reactor is greater than the thermal time constant of the switching element.

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