Electric conduction heating apparatus and electric conduction heating method

Abstract

To provide an electric conduction heating apparatus capable of performing a uniform heating by using a low-cost DC power supply.SOLUTION: An electric conduction heating apparatus 1 that heats a rotational electric machine 100 having a plurality of coils in an electric conduction, comprises: a DC power supply 3 that includes a terminal of a plus electrode and a minus electrode; a plurality of probes 5U, 5V, and 5W; a plurality of plus side switches +4U, +4V, and +4W; a plurality of minus side switches -4U, -4V, and -4W; and a control part 2 that changes an output voltage of a DC power supply in accordance with a temperature of a plurality of coils, and is equivalent a sum of a curent flowing in each coil in a one period by periodically switching a switch of the plurality of plus side switches and the plurality of minus side switches.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a resistance heating device and a resistance heating method. [Background technology]

[0002] As a method for fixing a coil wound around a stator core of a rotating electric machine to the stator core, there is a method of filling the space between the stator core and the coil with liquid thermosetting resin and heating and hardening the thermosetting resin. As a method for uniformly heating the thermosetting resin, a method has been disclosed in which the resistance of the coil is utilized to heat the coil by passing an electric current through it and the stator core is inductively heated to heat the thermosetting resin (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4887990 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional heating method requires two types of power sources, one for resistive heating and one for induction heating. Furthermore, the induction heating source requires an expensive AC power source, which results in high costs.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide an electric heating device that can perform uniform heating using an inexpensive DC power supply. [Means for solving the problem]

[0006] The electric heating device disclosed herein is an electric heating device that electrically heats a rotating electric machine having multiple coils by passing current through the multiple coils, and is equipped with a DC power supply having positive and negative terminals, multiple probes that supply current to each of the multiple coils, multiple positive side switches connected between the positive pole and the multiple probes, multiple negative side switches connected between the negative pole and the multiple probes, and a control unit that changes the output voltage of the DC power supply in accordance with the temperature of the multiple coils and periodically switches the multiple positive side switches and multiple negative side switches open and closed to equalize the sum of the currents flowing through each coil during one period. Effect of the Invention

[0007] The electric current heating device disclosed herein includes a DC power supply having positive and negative terminals, a plurality of probes that supply current to each of a plurality of coils, a plurality of positive side switches each connected between the positive pole and the plurality of probes, a plurality of negative side switches each connected between the negative pole and the plurality of probes, and a control unit that changes the output voltage of the DC power supply in accordance with the temperature of the multiple coils and periodically switches the multiple positive side switches and negative side switches open and closed to equalize the sum of the currents flowing through each coil during one period, thereby enabling uniform heating to be performed using an inexpensive DC power supply. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a rotating electric machine according to a first embodiment. [Diagram 2] 1 is a schematic diagram of a stator of a rotating electric machine according to a first embodiment. [Diagram 3] FIG. 1 is a configuration diagram of a resistance heating device according to a first embodiment. [Figure 4] 4 is a configuration diagram of a control unit of the electric resistance heating device according to the first embodiment. FIG. [Diagram 5] FIG. 2 is a diagram for explaining a current path in the first embodiment. [Figure 6]FIG. 2 is a diagram for explaining a current path in the first embodiment. [Figure 7] FIG. 2 is a diagram for explaining a current path in the first embodiment. [Figure 8] FIG. 4 is a diagram for explaining switch operation and current distribution in the resistance heating device according to the first embodiment. [Figure 9] 5 is a flowchart showing an operation for maintaining an appropriate temperature range in the resistance heating device according to the first embodiment. [Figure 10] 5 is a flowchart showing an operation for maintaining an appropriate temperature range in the resistance heating device according to the first embodiment. [Figure 11] FIG. 11 is a configuration diagram of a resistance heating device according to a second embodiment. [Figure 12] FIG. 11 is a diagram for explaining a current path in the second embodiment. [Figure 13] FIG. 11 is a diagram for explaining a current path in the second embodiment. [Figure 14] FIG. 11 is a diagram for explaining a current path in the second embodiment. [Figure 15] FIG. 10 is a diagram for explaining the operation of a switch in the electric resistance heating device according to the second embodiment. [Figure 16] FIG. 2 is a diagram illustrating an example of a hardware configuration of a control unit according to the first and second embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a detailed description will be given of an electric heating device according to an embodiment of the present disclosure with reference to the drawings. In addition, the same reference numerals in each drawing indicate the same or corresponding parts.

[0010] Embodiment 1 Fig. 1 is a cross-sectional view of a rotating electric machine according to embodiment 1. The rotating electric machine shown in Fig. 1 is an example of a rotating electric machine that is heated by a resistance heating device according to the present embodiment. Fig. 1 is a cross-sectional view in a direction parallel to a rotation axis center described later.

[0011] The rotating electric machine 100 includes an annular stator 110, a cylindrical rotor 120 disposed on the inner diameter side of the stator 110 with a gap between them, and a case 130 that houses them. Note that C in Fig. 1 indicates the rotation axis of the rotor 120. Hereinafter, a direction parallel to the rotation axis C is referred to as the axial direction, a direction perpendicular to the rotation axis C is referred to as the radial direction, and a direction rotating around the rotation axis C is referred to as the circumferential direction. Also, the inner diameter side is a direction approaching the rotation axis C in the radial direction, and the outer diameter side is a direction moving away from the rotation axis C in the radial direction.

[0012] The stator 110 is fixed to the inner diameter side of the case 130. The stator 110 has a stator core 111, a coil 112, a connection plate 113, an insulator 114, and a resin 115. The stator core 111 is made of electromagnetic steel plates laminated in the axial direction. The stator core 111 has teeth evenly arranged in the circumferential direction, and the coil 112 is wound around the teeth. The connection plate 113 is arranged at one end of the stator core 111 to supply current to the coil 112. The insulator 114 is arranged between the stator core 111 and the coil 112, and electrically insulates the stator core 111 and the coil 112 and conducts heat generated by the coil 112 to the stator core 111. The insulator 114 is, for example, an insulating tape, an insulating resin, or the like. Resin 115 is filled between stator core 111 and coil 112 and between coils 112, and is formed to ensure adhesion of coil 112, insulation between coils, and thermal conductivity. In addition, connection plate 113 is fixed to insulator 114 by resin 115.

[0013] Resin 115 is an insulating thermosetting resin, and is the target to be heated and cured by the electric heating device of this embodiment. Examples of resin 115 include unsaturated polyester resin, epoxy resin, polyphenylene sulfide resin, and liquid crystal polymer.

[0014] The rotor 120 has a shaft 121, a rotor core 122, and a permanent magnet 123. The rotor core 122 is made of electromagnetic steel plates laminated in the axial direction. The permanent magnets 123 are provided inside slots provided inside the rotor core 122 or on the surface of the rotor core 122. The shaft 121 is rotatably supported by a case 130 via bearings 133 at both axial ends.

[0015] The case 130 has a cylindrical case body 131 with a bottom that is open at one axial end, a disk-shaped lid 132 that covers the opening of the case body 131, and a bearing 133 that rotatably supports the shaft 121 of the rotor 120. The stator 110 is fixed to the inner diameter side of the peripheral wall of the case body 131. The bottom wall and the lid 132 of the case body 131 are each provided with a through hole near the rotation axis C through which the shaft 121 passes, and a bearing 133 is fixed to the inner diameter side of each through hole.

[0016] FIG. 2 is a schematic diagram of a stator in a rotating electric machine 100. The stator core of the stator 110 has a core back having an annular shape and a plurality of teeth 117 protruding from the core back to the inner diameter side. Thirty-six teeth 117 are uniformly provided in the circumferential direction. Coils 112 are wound around each of the 36 teeth 117. In the rotating electric machine of this embodiment, three-phase coils are wound around, and the coils 112 are U-phase, V-phase, and W-phase coils. Hereinafter, all coils are collectively referred to as coils 112, and coils of each phase are referred to as U-phase coil 112U, V-phase coil 112V, and W-phase coil 112W. Similarly, when the U-phase, V-phase, and W-phase are individually described in the connection plate 113, the power supply terminal 116 described later, the detection signal 8, and the like, U, V, and W are added to the end.

[0017] 2, any one of U-phase coils 112U, V-phase coils 112V, and W-phase coils 112W is wound around 36 teeth 117 in order. Twelve U-phase coils 112U are wound around each of 12 teeth 117, twelve V-phase coils 112V are wound around each of 12 teeth 117, and twelve W-phase coils 112W are wound around each of 12 teeth 117. One end of each of the twelve U-phase coils 112U is connected to U-phase connection plate 113U, one end of each of the twelve V-phase coils 112V is connected to V-phase connection plate 113V, and one end of each of the twelve W-phase coils 112W is connected to W-phase connection plate 113W. The other ends of the twelve U-phase coils 112U, the other ends of the twelve V-phase coils 112V, and the other ends of the twelve W-phase coils 112W are connected to each other. That is, the twelve U-phase coils 112U are connected in parallel to the connection plate 113U, the twelve V-phase coils 112V are connected in parallel to the connection plate 113V, and the twelve W-phase coils 112W are connected in parallel to the connection plate 113W. The rotating electric machine 100 according to this embodiment is configured with a three-phase AC winding in which three-phase coils are connected by Y-connection. The connection plate 113 is connected to a power supply terminal 116 for supplying a current to the connection plate 113 at one point in the circumferential direction. The stator shown in FIG. 2 is a distributed winding, but may be a concentrated winding. In addition, the number of teeth is not limited to this.

[0018] Coil 112 is wound around each of teeth 117 via insulator 114. Coil 112 and stator core 111 having teeth 117 are connected to each other via insulator 114 so as to be capable of thermal conduction. Wire connection plate 113 is connected to stator core 111 via resin 115 and insulator 114 so as to be capable of thermal conduction.

[0019] Next, a method of electrically heating the stator 110 of the rotating electric machine 100 according to this embodiment will be described. With the coils 112 wound around the teeth 117 of the stator core 111, liquid thermosetting resin is filled between the stator core 111 and the coils 112 and between the coils 112 themselves. The stator 110 is then heated to harden the thermosetting resin and form the resin 115. In this resin hardening process, the stator core 111 and the coils 112, and the coils 112 themselves are fixed to each other. The method of heating the stator 110 is an electrically heating method in which a current is passed through the coils 112, and the coils 112 are heated by the DC resistance component of the coils 112, thereby heating the stator 110.

[0020] 3 is a configuration diagram of an electric heating device according to this embodiment. The electric heating device 1 according to this embodiment has a control unit 2, a power source 3, positive side switches +4U, +4V, +4W, negative side switches -4U, -4V, -4W, and probes 5U, 5V, 5W. The control unit 2 outputs a voltage control signal 6 to the power source 3, and outputs a switch control signal 7 to the positive side switches +4U, +4V, +4W and the negative side switches -4U, -4V, -4W. The power source 3 is a DC power source having a positive terminal and a negative terminal, and outputs a voltage according to the signal level of the input voltage control signal 6.

[0021] One terminal of the positive side switch +4U is connected to the positive pole of power supply 3, and the other terminal is connected to probe 5U. One terminal of the negative side switch -4U is connected to the negative pole of power supply 3, and the other terminal is connected to probe 5U. One terminal of the positive side switch +4V is connected to the positive pole of power supply 3, and the other terminal is connected to probe 5V. One terminal of the negative side switch -4V is connected to the negative pole of power supply 3, and the other terminal is connected to probe 5V. One terminal of the positive side switch +4W is connected to the positive pole of power supply 3, and the other terminal is connected to probe 5W. One terminal of the negative side switch -4W is connected to the negative pole of power supply 3, and the other terminal is connected to probe 5W. The positive switches +4U, +4V, +4W and the negative switches -4U, -4V, -4W are composed of semiconductor elements such as relays or MOS-FETs (Metal-Oxide-Semiconductor Field-Effect Transistors), and have the function of switching the current path on and off. Note that from here on, the positive switches +4U, +4V, +4W and the negative switches -4U, -4V, -4W will also be referred to simply as switches.

[0022] A power supply terminal 116U of the rotating electric machine 100 is connected to the probe 5U. A power supply terminal 116V of the rotating electric machine 100 is connected to the probe 5V. A power supply terminal 116W of the rotating electric machine 100 is connected to the probe 5W. Thermistors 10U, 10V, and 10W are respectively installed near the power supply terminals 116U, 116V, and 116W of the rotating electric machine 100. Thermistors 10U, 10V, and 10W are temperature detectors that detect the temperatures of the power supply terminals 116U, 116V, and 116W, respectively. The temperatures of the power supply terminals detected by thermistors 10U, 10V, and 10W are transmitted to the control unit 2 as a detection signal 8.

[0023] 4 is a configuration diagram of the control unit of the electric heating device according to the present embodiment. The control unit 2 is composed of a PWM generating unit 11 that generates a PWM (Pulse Width Modulation) signal, a dead time control unit 12, and a voltage control signal generating unit 13. The PWM generating unit 11 includes a PWM signal generating unit (+U) 11a that generates a PWM signal that controls the operation of the plus side switch +4U, a PWM signal generating unit (-U) 11b that generates a PWM signal that controls the operation of the minus side switch -4U, a PWM signal generating unit (+V) 11c that generates a PWM signal that controls the operation of the plus side switch +4V, a PWM signal generating unit (-V) 11d that generates a PWM signal that controls the operation of the minus side switch -4V, a PWM signal generating unit (+W) 11e that generates a PWM signal that controls the operation of the plus side switch +4W, a PWM signal generating unit (-W) 11f that generates a PWM signal that controls the operation of the minus side switch -4W, and a PWM signal generating unit (dead time) 11g that generates a dead time signal.

[0024] The method of generating these PWM signals in the PWM generating unit 11 includes, for example, a method of synchronizing seven signals and generating them using the PWM function of a microcomputer, or a method of generating them using multiple timer ICs. However, the method of generating PWM signals is not limited to these.

[0025] The dead time control unit 12 includes dead time providing units 12a, 12b, 12c, 12d, 12e, and 12f that provide dead time to each of the PWM signals output from the PWM signal generating units 11a, 11b, 11c, 11d, 11e, and 11f based on the dead time signal generated by the PWM signal generating unit (dead time) 11g. The dead time control unit 12 outputs a switch control signal 7 in which the dead time is provided to the PWM signal output from the PWM generating unit 11.

[0026] The voltage control signal generating unit 13 includes a U-phase temperature upper limit comparator 14U, a V-phase temperature upper limit comparator 14V, a W-phase temperature upper limit comparator 14W, a U-phase temperature lower limit comparator 15U, a V-phase temperature lower limit comparator 15V, a W-phase temperature lower limit comparator 15W, an AND circuit 16, a voltage switching unit 17, and a protection unit 18. The U-phase temperature upper limit comparator 14U and the U-phase temperature lower limit comparator 15U receive a detection signal 8U from thermistor 10U. The V-phase temperature upper limit comparator 14V and the V-phase temperature lower limit comparator 15V receive a detection signal 8V from thermistor 10V. The W-phase temperature upper limit comparator 14W and the W-phase temperature lower limit comparator 15W receive a detection signal 8W from thermistor 10W. The voltage control signal generating unit 13 outputs a voltage control signal 6 to the power supply 3.

[0027] Next, the operation of the voltage control signal generating unit 13 will be described. For the sake of simplicity, a case where a current flows through the U-phase coil will be described. The current flowing in from the power supply terminal 116U of the stator 110 of the rotating electric machine 100 flows through the wiring board 113U, and the current output from the wiring board 113U is divided and flows through the twelve U-phase coils 112U connected in parallel. Therefore, the current is concentrated at the probe 5U and the power supply terminal 116U, and heat is generated due to the contact resistance between the probe 5U and the power supply terminal 116U and the current flowing there. The amount of heat generated is greater than the amount of heat generated by the current divided and flowing through the U-phase coil 112U and the direct current resistance of the U-phase coil 112U. The thermistor 10U detects the temperature of the power supply terminal 116U. Therefore, the temperature of the power supply terminal 116U detected by the thermistor 10U is correlated with the temperature of the U-phase coil 112U.

[0028] The temperature detected by thermistor 10U is input as detection signal 8U to voltage control signal generator 13. Detection signal 8U indicating the temperature of power supply terminal 116U is input to U-phase temperature upper limit comparator 14U and U-phase temperature lower limit comparator 15U. A preset upper temperature threshold is stored in U-phase temperature upper limit comparator 14U. A preset lower temperature threshold is stored in U-phase temperature lower limit comparator 15U.

[0029] The upper and lower temperature thresholds are set based on the characteristics of the thermosetting resin that is the material of resin 115. The upper and lower temperature thresholds are set appropriately depending on the type of thermosetting resin, the positional relationship between the coil and the probe, and the like.

[0030] The U-phase temperature upper limit comparator 14U outputs a "H" level signal to the AND circuit 16 and the voltage switching unit 17 when the value of the detection signal 8U exceeds the upper temperature threshold. In addition, the U-phase temperature upper limit comparator 14U outputs a "L" level signal to the AND circuit 16 and the voltage switching unit 17 when the value of the detection signal 8U is equal to or lower than the upper temperature threshold. The U-phase temperature lower limit comparator 15U outputs a "H" level signal to the AND circuit 16 when the value of the detection signal 8U is below the lower temperature threshold. In addition, the U-phase temperature lower limit comparator 15U outputs a "L" level signal to the AND circuit 16 when the value of the detection signal 8U is equal to or higher than the lower temperature threshold.

[0031] So far, we have explained the case where current flows through the U-phase coil, but even if current flows through the V-phase coil and the W-phase coil, V-phase temperature upper limit comparator 14V and W-phase temperature upper limit comparator 14W operate in the same manner as U-phase temperature upper limit comparator 14U, and V-phase temperature lower limit comparator 15V and W-phase temperature lower limit comparator 15W operate in the same manner as U-phase temperature lower limit comparator 15U.

[0032] The voltage switching unit 17 has two input terminals and one output terminal. The two input terminals are set to preset voltage values ​​VH and VL, respectively. The relationship between the two voltage values ​​is VH>VL. The voltage switching unit 17 outputs a voltage of VL from the output terminal when any one of the U-phase temperature upper limit comparator 14U, the V-phase temperature upper limit comparator 14V, and the W-phase temperature upper limit comparator 14W outputs an "H" level signal. In other cases, the voltage switching unit 17 outputs a voltage of VH from the output terminal. The protection unit 18 has two input terminals and one output terminal. One input terminal of the protection unit 18 is connected to the output terminal of the voltage switching unit 17. The other input terminal of the protection unit 18 is set to a ground potential. The voltage switching unit 17 and the protection unit 18 output one of the signals input to the two input terminals from the output terminal.

[0033] The outputs of U-phase temperature upper limit comparator 14U, V-phase temperature upper limit comparator 14V, and W-phase temperature upper limit comparator 14W are input to one input terminal of AND circuit 16. The outputs of U-phase temperature lower limit comparator 15U, V-phase temperature lower limit comparator 15V, and W-phase temperature lower limit comparator 15W are input to the other input terminal of AND circuit 16. When "H" level signals are input to the two input terminals simultaneously, AND circuit 16 outputs an "H" level signal. In all other cases, AND circuit 16 outputs an "L" level signal. The output signal of AND circuit 16 is a signal that switches the contacts of protection unit 18.

[0034] When the signal input from the AND circuit 16 is “L”, the protection unit 18 outputs the voltage input from the voltage switching unit 17 as the voltage control signal 6. When the signal input from the AND circuit 16 is “H”, the protection unit 18 outputs the voltage of the ground potential as the voltage control signal 6.

[0035] The power supply 3 initially outputs a voltage of a predetermined initial value. Then, when a voltage control signal 6 is input from the voltage control signal generating unit 13, the power supply 3 performs the following operation. When VL is input as the voltage control signal 6, the power supply 3 reduces the output voltage from the initial value voltage to a predetermined voltage. When VH is input as the voltage control signal 6, the power supply 3 increases the output voltage to the initial value voltage. When a ground potential voltage is input as the voltage control signal 6, the power supply 3 reduces the output voltage to 0V and stops current output.

[0036] 4, a circuit for generating the voltages VH and VL of the voltage control signal generating unit 13 is omitted. The voltages VH and VL can be generated by dividing the output voltage of a driving power supply for the electric heating device (not shown) using any resistor.

[0037] Next, the current path including the rotating electric machine in the resistance heating device of this embodiment will be described. Figures 5 to 7 are diagrams for explaining the current path in this embodiment. In Figures 5 to 7, the current path indicated by the dashed line indicates the current path from the positive pole of the power source 3 of the resistance heating device 1 to the return to the negative pole. Note that the connection plate 113 is omitted in Figures 5 to 7.

[0038] Figure 5 shows the current paths when switches -4U, +4V, and +4W are closed and switches +4U, -4V, and -4W are open. The current flowing from the positive pole of power supply 3 flows from switch +4V through probe 5V and power supply terminal 116V to V-phase coil 112V. Similarly, the current flowing from the positive pole of power supply 3 flows from switch +4W through probe 5W and power supply terminal 116W to W-phase coil 112W. The currents flowing in V-phase coil 112V and W-phase coil 112W join together and return to the negative pole of power supply 3 via U-phase coil 112U.

[0039] Figure 6 shows the current paths when switches +4U, -4V, and +4W are closed and switches -4U, +4V, and -4W are open. The current flowing from the positive pole of the power supply 3 flows from switch +4U through probe 5U and power supply terminal 116U to U-phase coil 112U. Similarly, the current flowing from the positive pole of the power supply 3 flows from switch +4W through probe 5W and power supply terminal 116W to W-phase coil 112W. The currents flowing in U-phase coil 112U and W-phase coil 112W join together and return to the negative pole of the power supply 3 through V-phase coil 112V.

[0040] Figure 7 shows the current paths when switches +4U, +4V, and -4W are closed and switches -4U, -4V, and +4W are open. The current flowing from the positive pole of power supply 3 flows from switch +4U through probe 5U and power supply terminal 116U to U-phase coil 112U. Similarly, the current flowing from the positive pole of power supply 3 flows from switch +4V through probe 5V and power supply terminal 116V to V-phase coil 112V. The currents flowing in U-phase coil 112U and V-phase coil 112V join together and return to the negative pole of power supply 3 through W-phase coil 112W.

[0041] In the current paths shown in FIGS. 5 to 7, the coils of any two phases of the three-phase coils are connected in parallel, and the coil of the remaining phase is connected in series to the coils of the two phases connected in parallel.

[0042] FIG. 8 is a diagram for explaining the operation of the switches and the current distribution in the electric heating device of this embodiment. The operation of the switches shown in FIG. 8 is the basic operation of uniform heating in the electric heating device of this embodiment. In FIG. 8, the horizontal direction is time, and the vertical direction indicates the closed state of each switch +4U, -4U, +4V, -4V, +4W, -4W as ON and the open state as OFF. Also, in FIG. 8, DT indicates the dead time signal generated by the PWM signal generating unit (dead time) 11g. Here, T1, T2, and T3 have the same time width, and are the time widths during which each switch is maintained in the ON or OFF state. td1, td2, and td3 are time periods provided to prevent a short circuit between the negative pole and the positive pole of the power source 3, and are time periods during which all switches are turned OFF.

[0043] Here, T1, T2, and T3 are set to, for example, 20 to 60 seconds. Also, td1, td2, and td3 are set to, for example, 0.2 to 1.0 seconds. As described later, current flows non-uniformly through each coil during the times T1, T2, and T3, so that the heat generated by the coils during those times becomes non-uniform. The times T1, T2, and T3 are set to average the heat generated by all the coils during one cycle operation. Also, the times td1, td2, and td3 are set to a time that can ensure the prevention of short circuits based on the responsiveness of the switches. Note that the time settings shown are merely examples, and may vary greatly depending on the size of the rotating electric machine to be heated.

[0044] In FIG. 8, the time period indicated by current path 1 corresponds to the open / closed state of the switch shown in FIG. 5, the time period indicated by current path 2 corresponds to the open / closed state of the switch shown in FIG. 6, and the time period indicated by current path 3 corresponds to the open / closed state of the switch shown in FIG. 7. As shown in FIG. 8, the open / closed states of the switch shown in FIGS. 5 to 7 are repeated to form one cycle. The sum of the currents flowing through the coils of each phase during this one cycle operation is equal. In the current heating device of this embodiment, this cycle is performed n times arbitrarily. In FIG. 8, the values ​​shown in percentages represent the ratio of the current flowing through each switch when the output current of the power source 3 is set to 100%.

[0045] 8, during the time period of current path 1, as described in FIG 5, the currents flowing from the positive pole of power supply 3 to V-phase coil 112V and W-phase coil 112W join together and return to the negative pole of power supply 3 via U-phase coil 112U. At this time, since the DC resistance value of V-phase coil 112V and the DC resistance value of W-phase coil 112W are equal, 50% of the current flows through V-phase coil 112V and W-phase coil 112W, and 100% of the current flows through U-phase coil 112U where the currents flowing through these two coils join. Note that during the time period of current path 1, the switches indicated by 0% indicate a state in which the switches are OFF, i.e., open, and no current flows.

[0046] 8, during the time period of current path 2, as described in FIG 6, the currents flowing from the positive pole of power supply 3 to U-phase coil 112U and W-phase coil 112W join together and return to the negative pole of power supply 3 via V-phase coil 112V. At this time, since the DC resistance value of U-phase coil 112U and the DC resistance value of W-phase coil 112W are equal, 50% of the current flows through U-phase coil 112U and W-phase coil 112W, and 100% of the current flows through V-phase coil 112V where the currents flowing through these two coils join together.

[0047] 8, during the time period of current path 3, as described in FIG 7, the currents flowing from the positive pole of power supply 3 to U-phase coil 112U and V-phase coil 112V join together and return to the negative pole of power supply 3 via W-phase coil 112W. At this time, because the DC resistance value of U-phase coil 112U is equal to the DC resistance value of V-phase coil 112V, 50% of the current flows through U-phase coil 112U and V-phase coil 112V, and 100% of the current flows through W-phase coil 112W where the currents flowing through these two coils join together.

[0048] The control unit 2 of the electric current heating device 1 of this embodiment periodically switches the opening and closing of a plurality of positive side switches and a plurality of negative side switches, periodically switching the connection relationship of the three-phase coils in which any two phase coils are connected in parallel between the positive and negative poles of the power source, and the coil of the remaining phase is connected in series to the two phase coils connected in parallel. In the electric current heating device of this embodiment, the sum of the currents flowing through the coils of each phase during one cycle operation is made equal, but the sum of the currents flowing through the coils of each phase is not limited to being completely equal. As long as the thermosetting resin is heated to a certain degree uniformly in the stator, the sum of the currents flowing through the coils of each phase may be slightly different.

[0049] Next, the operation for maintaining the appropriate temperature range in the electric current heating device of this embodiment will be described. Figures 9 and 10 are flowcharts showing the operation for maintaining the appropriate temperature range in the electric current heating device of this embodiment. The flowcharts shown in Figures 9 and 10 are connected to each other at the positions indicated by A, B, C, and D. The temperature control operation shown in Figures 9 and 10 is an operation for maintaining the appropriate temperature range in the basic operation of uniform heating in which the cycle of electric current heating shown in Figure 8 is performed n times. That is, the electric current heating device of this embodiment performs the operation for maintaining the appropriate temperature range shown in Figures 9 and 10 while performing the basic uniform operation shown in Figure 8.

[0050] In step S01, the control unit 2 causes the power supply 3 to output an initial voltage. The initial voltage output from the power supply 3 is a voltage value of VH that is predetermined in the control unit 2. Next, in step S02, the control unit 2 receives the temperature of the power supply terminal 116. Hereinafter, the power supply terminal 116 means all of the power supply terminals 116U, 116V, and 116W. Next, in step S03, the control unit 2 determines whether the output of the AND circuit 16 is "L" or not. In step S03, if the output of the AND circuit 16 is "L" (YES), the protection unit 18 can output the signal of the voltage switching unit 17 as the voltage control signal 6, so the process proceeds to step S04. In step S03, if the output of the AND circuit 16 is "H" (NO), the temperature of any one of the power supply terminals 116 exceeds the upper temperature threshold value, and the temperature of any other power supply terminal 116 falls below the lower temperature threshold value. In this case, proceed to step S05 to correct the malfunction, such as the connection between the resistance heating device and the rotating electric machine. After the malfunction is corrected in step S05, return to step S01. Note that, if the output of the AND circuit 16 is "H" in step S03, the output of the protection unit 18 becomes the ground potential. Since the voltage control signal 6 becomes the ground potential, the power supply 3 reduces the output voltage to 0 V and stops current output.

[0051] In step S04, the control unit 2 determines whether or not the heating time has ended. In step S04, the end of the heating time means that n cycles of the basic operation of the electrical heating shown in FIG. 8 have ended. In step S04, if the heating time has ended (YES), the heating operation ends. In step S04, if the heating time has not ended (NO), the process proceeds to step S06.

[0052] In step S06, the control unit 2 determines whether the temperature of the power supply terminal 116 has exceeded the upper temperature threshold. Whether the temperature of the power supply terminal 116 has exceeded the upper temperature threshold can be determined by whether any of the outputs of the U-phase temperature upper limit comparator 14U, the V-phase temperature upper limit comparator 14V, and the W-phase temperature upper limit comparator 14W is an "H" level signal. In step S06, if the temperature of the power supply terminal 116 has exceeded the upper temperature threshold (YES), the process proceeds to step S07. In step S06, if the temperature of the power supply terminal 116 is equal to or lower than the upper temperature threshold (NO), the process returns to step S02. If the process loops from step S02 to step S06 and the heating operation is finally terminated from step S04, the temperature of the power supply terminal 116 is equal to or lower than the upper temperature threshold and the basic operation of electrical heating is completed.

[0053] When the process proceeds to step S07, the temperature of the power supply terminal 116 exceeds the upper temperature threshold, so the control unit 2 reduces the output voltage of the power supply 3 in step S07. Specifically, since an "H" level signal is input to the voltage switching unit 17, the output of the voltage switching unit 17 switches to VL. Therefore, the voltage control signal 6 becomes VL, so the power supply 3 reduces the output voltage from the initial voltage value to a predetermined voltage.

[0054] Next, in step S08, the control unit 2 receives the temperature of the power supply terminal 116. Next, in step S09, the control unit 2 determines whether or not the output of the AND circuit 16 is "L". If the output of the AND circuit 16 is "L" (YES) in step S09, the protection unit 18 can output the signal of the voltage switching unit 17 as the voltage control signal 6, so the process proceeds to step S10. If the output of the AND circuit 16 is "H" (NO) in step S09, the process proceeds to step S05 to correct the malfunction, similar to step S03.

[0055] In step S10, the control unit 2 determines whether the temperature of the power supply terminal 116 is within the appropriate range. Whether the temperature of the power supply terminal 116 is within the appropriate range can be determined by whether all of the outputs of the U-phase temperature upper limit comparator 14U, the V-phase temperature upper limit comparator 14V, the W-phase temperature upper limit comparator 14W, the U-phase temperature lower limit comparator 15U, the V-phase temperature lower limit comparator 15V, and the W-phase temperature lower limit comparator 15W are "L" level signals. In step S10, if the temperature of the power supply terminal 116 is within the appropriate range (YES), the process proceeds to step S11. In step S10, if the temperature of the power supply terminal 116 is outside the appropriate range (NO), the process proceeds to step S12. In the case where the process proceeds to step S11, the control unit 2 determines whether the heating time has ended in step S11. In the case where the heating time has ended in step S11 (YES), the heating operation is ended. In the case where the heating time has not ended in step S11 (NO), the process returns to step S08.

[0056] If the process proceeds to step S12, the temperature of the power supply terminal 116 is outside the appropriate range. In this case, since the output voltage of the power supply 3 has been reduced from the initial value in step S07, the temperature of the power supply terminal 116 is equal to or lower than the upper temperature threshold and is lower than the lower temperature threshold. Therefore, in step S12, the control unit 2 returns the output voltage of the power supply 3 to the initial value. Specifically, since an "L" level signal is input to the voltage switching unit 17, the output of the voltage switching unit 17 is switched to VH. Therefore, the voltage control signal 6 becomes VH, and the power supply 3 returns the output voltage to the initial value.

[0057] Next, in step S13, the control unit 2 receives the temperature of the power supply terminal 116. Next, in step S14, the control unit 2 determines whether or not the output of the AND circuit 16 is "L". If the output of the AND circuit 16 is "L" in step S14 (YES), the protection unit 18 can output the signal of the voltage switching unit 17 as the voltage control signal 6, so the process proceeds to step S15. If the output of the AND circuit 16 is "H" in step S14 (NO), the process proceeds to step S05 to correct the malfunction, similar to step S03.

[0058] In step S15, the control unit 2 determines whether or not the temperature of the power supply terminal 116 is within the appropriate range. If the temperature of the power supply terminal 116 is within the appropriate range in step S15 (YES), the process proceeds to step S16. If the temperature of the power supply terminal 116 is outside the appropriate range in step S15 (NO), the process proceeds to step S17. When proceeding to step S16, the control unit 2 determines whether or not the heating time has ended in step S16. If the heating time has ended in step S16 (YES), the heating operation ends. If the heating time has not ended in step S16 (NO), the process returns to step S13.

[0059] When the process proceeds to step S17, the control unit 2 determines in step S17 whether or not the temperature of the power supply terminal 116 has exceeded the upper temperature threshold. If the temperature of the power supply terminal 116 has exceeded the upper temperature threshold (YES) in step S17, the process returns to step S07. If the temperature of the power supply terminal 116 is equal to or lower than the upper temperature threshold (NO) in step S17, the process returns to step S12.

[0060] In the basic operation of the electrical heating shown in Fig. 8, the electrical heating device of this embodiment periodically switches the opening and closing of multiple positive side switches and multiple negative side switches to equalize the sum of the currents flowing through each coil during one period, thereby enabling the stator to be heated uniformly. Also, in the operation for maintaining the appropriate temperature range shown in Fig. 9 and Fig. 10, the output voltage of the power supply can be changed according to the coil temperature, thereby allowing the temperature of the stator to be set within a temperature range suitable for the characteristics of the thermosetting resin.

[0061] In this way, the resistance heating device of this embodiment is equipped with one DC power supply and multiple positive and negative switches that switch the current path, and during resistance heating, the output voltage of the DC power supply is changed according to the temperature of the multiple coils, and the multiple positive and negative switches are periodically opened and closed to equalize the sum of the currents flowing through each coil during one period, so that uniform heating can be performed using an inexpensive DC power supply.

[0062] In this embodiment, the temperature of the power supply terminal of each phase is detected to detect the temperature of the coil of each phase of the rotating electric machine. The location where the temperature is detected may be the coil itself of each phase or the connection plate, as long as it is a part of the rotating electric machine whose temperature correlates with the temperature of the coil of each phase. The upper temperature threshold and the lower temperature threshold can be appropriately set according to the location where the temperature is detected.

[0063] In addition, in this embodiment, the electric current heating device has been described as electrically heating a rotating electric machine having a three-phase coil. The rotating electric machine performing electric current heating may be a rotating electric machine having a plurality of coils of two or more phases. In the case of a rotating electric machine having a two-phase coil, when the opening and closing of the plurality of positive side switches and the plurality of negative side switches are periodically switched, the direction of the current flowing through the coil is merely reversed periodically, but the stator can be heated uniformly. In addition, the appropriate temperature range can be maintained by performing the series of operations described using FIG. 9 and FIG. 10.

[0064] Embodiment 2 In the first embodiment, the rotating electric machine which is resistively heated by the resistive heating device is a rotating electric machine with three-phase AC windings in which three-phase coils are connected in a Y connection. The rotating electric machine which is resistively heated by the resistive heating device according to the second embodiment is a rotating electric machine with three-phase AC windings in which three-phase coils are connected in a delta connection. The configuration of the resistive heating device according to this embodiment is similar to the configuration of the resistive heating device according to the first embodiment.

[0065] FIG. 11 is a configuration diagram of the electric heating device according to the present embodiment. The electric heating device 1 according to the present embodiment has a control unit 2, a power source 3, positive side switches +4U, +4V, +4W, negative side switches -4U, -4V, -4W, and probes 5U, 5V, 5W. The control unit 2 outputs a voltage control signal 6 to the power source 3, and outputs a switch control signal 7 to the positive side switches +4U, +4V, +4W and the negative side switches -4U, -4V, -4W. The power source 3 is a DC power source having a positive terminal and a negative terminal, and outputs a voltage according to the signal level of the input voltage control signal. The configuration of the electric heating device 1 of the present embodiment shown in FIG. 11 is the same as the configuration of the electric heating device of the first embodiment, so a detailed description will be omitted.

[0066] A power feed terminal 116U of the rotating electric machine 100 is connected to the probe 5U. A power feed terminal 116V of the rotating electric machine 100 is connected to the probe 5V. A power feed terminal 116W of the rotating electric machine 100 is connected to the probe 5W. Thermistors 10U, 10V, and 10W are installed near the power feed terminals 116U, 116V, and 116W of the rotating electric machine 100, respectively. Thermistors 10U, 10V, and 10W detect the temperatures of the power feed terminals 116U, 116V, and 116W, respectively. The temperatures of the power feed terminals detected by thermistors 10U, 10V, and 10W are transmitted to the control unit 2 as a detection signal 8.

[0067] In the rotating electric machine 100 of this embodiment, three-phase coils are connected in a delta connection. In this rotating electric machine 100, the stator core has a core back of an annular shape and a plurality of teeth protruding from the core back to the inner diameter side. Thirty-six teeth are uniformly provided in the circumferential direction. Twelve U-phase coils 112U are wound around each of the 12 teeth, twelve V-phase coils 112V are wound around each of the 12 teeth, and twelve W-phase coils 112W are wound around each of the 12 teeth. In the rotating electric machine 100 of this embodiment, as shown in FIG. 11, one end of the 12 U-phase coils 112U is connected to a U-phase connection plate 113U, and the other end is connected to a V-phase connection plate 113V. One end of each of the twelve V-phase coils 112V is connected to a V-phase connection plate 113V, and the other end is connected to a W-phase connection plate 113W. One end of each of the twelve W-phase coils 112W is connected to a W-phase connection plate 113W, and the other end is connected to a U-phase connection plate 113U. That is, the twelve U-phase coils 112U are connected in parallel between the connection plate 113U and the connection plate 113V, the twelve V-phase coils 112V are connected in parallel between the connection plate 113V and the connection plate 113W, and the twelve W-phase coils 112W are connected in parallel between the connection plate 113W and the connection plate 113U. The rotating electric machine 100 according to the present embodiment is configured with a three-phase AC winding in which three-phase coils are connected in a delta connection.

[0068] Next, the current path including the rotating electric machine in the resistance heating device of this embodiment will be described. Figures 12 to 14 are diagrams for explaining the current path in this embodiment. In Figures 12 to 14, the current path shown by the dashed line indicates the current path from the positive pole of the power source 3 of the resistance heating device 1 to the negative pole returned to. Note that the connection plate 113 is omitted in Figures 12 to 14.

[0069] 12 shows the current paths when switches +4U and -4V are closed and switches -4U, +4V, +4W and -4W are open. The current flowing from the positive pole of power supply 3 is branched from switch +4U via probe 5U and power supply terminal 116U to U-phase coil 112U and W-phase coil 112W. The current flowing through W-phase coil 112W is merged with the current flowing through U-phase coil 112U via V-phase coil 112V and returns to the negative pole of power supply 3. If the DC resistance values ​​of the three phase coils are equal, the current flowing only through U-phase coil 112U is approximately twice the current flowing through W-phase coil 112W and V-phase coil 112V. For example, when the output current of power supply 3 is 100%, the current flowing only through U-phase coil 112U is approximately 67%, and the current flowing through W-phase coil 112W and V-phase coil 112V is approximately 33%.

[0070] FIG. 13 shows the current paths when switches +4V and -4W are closed and switches +4U, -4U, -4V and +4W are open. The current flowing from the positive pole of power supply 3 is branched and flows from switch +4V via probe 5V and power supply terminal 116V to U-phase coil 112U and V-phase coil 112V. The current flowing through U-phase coil 112U is joined with the current flowing through V-phase coil 112V via W-phase coil 112W and returns to the negative pole of power supply 3. If the DC resistance values ​​of the three phase coils are equal, the current flowing only through V-phase coil 112V is approximately twice the current flowing through U-phase coil 112U and W-phase coil 112W.

[0071] 14 shows the current paths when switches -4U and +4W are closed and switches +4U, +4V, -4V and -4W are open. The current flowing from the positive pole of power supply 3 is branched from switch +4W via probe 5W and power supply terminal 116V to V-phase coil 112V and W-phase coil 112W. The current flowing through V-phase coil 112V is joined with the current flowing through W-phase coil 112W via U-phase coil 112U and returns to the negative pole of power supply 3. If the DC resistance values ​​of the three phase coils are equal, the current flowing only through W-phase coil 112W is approximately twice the current flowing through V-phase coil 112V and U-phase coil 112U.

[0072] In the current paths shown in FIGS. 12 to 14, the coils of any two phases of the three-phase coils are connected in series, and the coil of the remaining phase is connected in parallel to the coils of the two phases connected in series.

[0073] FIG. 15 is a diagram for explaining the operation of the switches in the electric heating device of this embodiment. The operation of the switches shown in FIG. 15 is the basic operation of electric heating in the electric heating device of this embodiment. In FIG. 15, the horizontal direction is time, and the vertical direction indicates the closed state of each switch +4U, -4U, +4V, -4V, +4W, -4W as ON and the open state as OFF. Also, in FIG. 15, DT indicates the dead time signal generated by the PWM signal generating unit (dead time) 11g. Here, T1, T2, and T3 have the same time width, and are the time widths during which each switch is maintained in the ON or OFF state. td1, td2, and td3 are time periods provided to prevent a short circuit between the negative pole and the positive pole of the power source 3, and are time periods during which all switches are turned OFF.

[0074] In Fig. 15, the time period indicated by current path 1 corresponds to the open / closed state of the switch shown in Fig. 12, the time period indicated by current path 2 corresponds to the open / closed state of the switch shown in Fig. 13, and the time period indicated by current path 3 corresponds to the open / closed state of the switch shown in Fig. 14. As shown in Fig. 15, the open / closed states of the switch shown in Figs. 12 to 14 are repeated to form one cycle. The sum of the currents flowing through the coils of each phase during this one cycle operation is equal. In the resistance heating device of this embodiment, this cycle is performed an arbitrary n times.

[0075] The control unit 2 of the electric current heating device 1 of this embodiment periodically switches the opening and closing of multiple positive side switches and multiple negative side switches, thereby periodically switching the connection relationship of the three-phase coils such that the coils of any two phases of the three-phase coil are connected in series between the positive and negative poles of the power source, and the coil of the remaining phase is connected in parallel to the coils of the two phases connected in series.

[0076] The configuration of the resistance heating device of this embodiment is similar to that of the resistance heating device of embodiment 1. Therefore, in the basic operation of performing the resistance heating cycle n times shown in Fig. 15, the operation for maintaining the appropriate temperature range is similar to the flow charts shown in Figs. 9 and 10 of embodiment 1. That is, the resistance heating device of this embodiment performs the operation for maintaining the appropriate temperature range shown in Figs. 9 and 10 of embodiment 1 while performing the basic operation of uniform heating shown in Fig. 15, in a superimposed manner.

[0077] In the basic operation of the electrical heating shown in Fig. 15, the electrical heating device of this embodiment periodically switches the opening and closing of multiple positive side switches and multiple negative side switches to equalize the sum of the currents flowing through each coil during one period, thereby enabling the stator to be heated uniformly. Also, in the operation for maintaining the appropriate temperature range shown in Figs. 9 and 10, the output voltage of the power supply can be changed according to the coil temperature, thereby allowing the temperature of the stator to be set within a temperature range suitable for the characteristics of the thermosetting resin.

[0078] In this way, the resistance heating device of this embodiment is equipped with one DC power supply and multiple positive and negative switches that switch the current path, and during resistance heating, the output voltage of the DC power supply is changed according to the temperature of the multiple coils, and the multiple positive and negative switches are periodically opened and closed to equalize the sum of the currents flowing through each coil during one period, so that uniform heating can be performed using an inexpensive DC power supply.

[0079] The control unit 2 of the electric current heating device according to the first and second embodiments is composed of a processor 50 and a storage device 51, as shown in FIG. 16, which is an example of hardware. For example, the PWM generating unit 11, the dead time control unit 12, and the voltage control signal generating unit 13 may be realized by using the functions of the processor 50. Although not shown, the storage device includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory. Also, instead of the flash memory, an auxiliary storage device such as a hard disk may be included. The processor 50 executes a program input from the storage device 51. In this case, the program is input from the auxiliary storage device to the processor 50 via the volatile storage device. Also, the processor 50 may output data such as a calculation result to the volatile storage device of the storage device 51, or may store data in the auxiliary storage device via the volatile storage device.

[0080] While the present disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not exemplified are assumed within the scope of the technology disclosed in this specification, including, for example, modifying, adding, or omitting at least one component, and further, extracting at least one component and combining it with a component of another embodiment. [Explanation of symbols]

[0081] 1 Electrical heating device, 2 Control unit, 3 Power supply, +4U, +4V, +4W Positive side switch, -4U, -4V, -4W Negative side switch, 5U, 5V, 5W Probe, 6 Voltage control signal, 7 Switch control signal, 8, 8U, 8V, 8W Detection signal, 11 PWM generation unit, 12 Dead time control unit, 13 Voltage control signal generation unit, 16 AND circuit, 17 Voltage switching unit, 18 Protection unit, 50 Processor, 51 Storage device, 100 Rotating electric machine, 110 Stator, 111 Stator core, 112, 112U, 112V, 112W Coil, 113, 113U, 113V, 113W Wiring board, 114 Insulator, 115 Resin, 116, 116U, 116V, 116W Power supply terminal, 117 Teeth, 120 Rotor, 121 shaft, 122 rotor core, 123 permanent magnet, 130 case, 131 case body, 132 cover, 133 bearing.

Claims

1. A resistive heating device for electrically heating a rotating electric machine having a plurality of coils by passing current through the plurality of coils, the resistive heating device comprising: A DC power source having positive and negative terminals; A plurality of probes for supplying current to the respective coils; a plurality of positive side switches respectively connected between the positive pole and the plurality of probes; A plurality of negative side switches respectively connected between the negative pole and the plurality of probes; a control unit that changes the output voltage of the DC power supply in accordance with the temperatures of the plurality of coils, and that periodically switches the opening and closing of the plurality of positive side switches and the plurality of negative side switches to equalize the sum of the currents flowing through each of the coils during one cycle.

2. the plurality of coils are three-phase coils; The control unit periodically switches the opening and closing of the plurality of positive side switches and the plurality of negative side switches to periodically switch a connection relationship of the three-phase coils such that the coils of any two phases of the three-phase coils are connected in parallel between the positive pole and the negative pole of the DC power source and the coil of the remaining phase is connected in series to the coils of the two phases connected in parallel.

3. the plurality of coils are three-phase coils; The control unit periodically switches between opening and closing the plurality of positive side switches and the plurality of negative side switches to periodically switch a connection relationship of the three-phase coils such that the coils of any two phases of the three-phase coils are connected in series between the positive pole and the negative pole of the DC power source and the coil of the remaining phase is connected in parallel to the coils of the two phases connected in series.

4. 4. The electric heating device according to claim 1, further comprising a temperature detector for detecting the temperature of the plurality of coils or the temperature of a portion of the rotating electric machine whose temperature is correlated with the temperature of the plurality of coils.

5. A method for electrically heating a rotating electric machine having a plurality of coils by passing current through the plurality of coils, the method comprising the steps of: An electric current heating method, characterized in that the voltage applied to the coils is changed in accordance with the temperature of the multiple coils, and the current path of the current flowing through the multiple coils is periodically switched to make the sum of the current flowing through each of the coils equal during one period.

6. the plurality of coils are three-phase coils; The resistance heating method according to claim 5, characterized in that a current path is periodically switched so that the coils of any two phases of the three-phase coil are connected in parallel and the coil of the remaining phase is connected in series with the coils of the two phases connected in parallel.

7. the plurality of coils are three-phase coils; The resistance heating method according to claim 5, characterized in that a current path is periodically switched so that the coils of any two phases of the three-phase coil are connected in series and the coil of the remaining phase is connected in parallel to the coils of the two phases connected in series.

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