Anomaly detection circuit and motor drive device

Abstract

The present invention provides an abnormality detection circuit and motor drive device capable of accurately detecting abnormalities such as wire breaks. [Solution] The abnormality detection circuit 18 of the motor drive device 10 includes a resistor circuit 46 that is Δ-connected or Y-connected, and an output circuit 56 that outputs at least one of the following signals: a first signal S1 which is a signal corresponding to the current flowing through a first electrical resistor 48U, a second signal S2 which is a signal corresponding to the current flowing through a second electrical resistor 48V, and a third signal S3 which is a signal corresponding to the current flowing through a third electrical resistor 48W.

Description

Technical Field

[0001] The present disclosure relates to an abnormality detection circuit and a motor drive device.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2013-247754 discloses a drive control device for an electric motor. In this drive control device, an abnormality in an output line from a switching element of an inverter device to a winding of the electric motor is detected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A technique capable of detecting an abnormality such as a disconnection well is desired.

[0005] The present disclosure aims to solve the above-described problems.

Means for Solving the Problems

[0006] A first aspect of this disclosure is an abnormality detection circuit comprising: a first conduction path that conducts a first phase terminal provided on a three-phase motor to a first power line which is one of a pair of DC power lines; a second conduction path that conducts a second phase terminal provided on the three-phase motor to the first power line; a third conduction path that conducts a third phase terminal provided on the three-phase motor to the first power line; a resistor circuit that is Δ-connected or Y-connected and electrically connected to the first conduction path, the second conduction path, and the third conduction path; a first electrical resistor provided in a first partial path which is a portion of the first conduction path located between the resistor circuit and the first power line; and the resistor circuit and the first electrical resistor in the second conduction path. The circuit includes a second electrical resistor provided in a second partial path which is the portion located between the power line and the power line; a third electrical resistor provided in a third partial path which is the portion of the third conducting path which is located between the resistor circuit and the first power line; a fourth electrical resistor provided in a fourth conducting path which connects one of the first phase terminal, the second phase terminal and the third phase terminal to the second power line, which is the other of the pair of DC power lines; and an output circuit which outputs at least one of the following signals: a first signal which is a signal corresponding to the current flowing through the first electrical resistor; a second signal which is a signal corresponding to the current flowing through the second electrical resistor; and a third signal which is a signal corresponding to the current flowing through the third electrical resistor.

[0007] A second aspect of the present disclosure is a motor drive device comprising: an abnormality detection circuit; an inverter for driving the three-phase motor; and a determination unit that performs abnormality determination based on the signal output from the abnormality detection circuit, wherein the determination unit performs the abnormality determination with the inverter turned off. [Effects of the Invention]

[0008] According to this disclosure, abnormalities such as broken wires can be detected effectively. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a circuit diagram of a motor drive device according to one embodiment. [Figure 2]Figure 2A is a partial circuit diagram showing the path of DC current under normal conditions, and Figure 2B is a partial circuit diagram showing the path of DC current when a U-phase loss occurs. [Figure 3] Figure 3A is a partial circuit diagram showing the path of the DC current when the V phase is out of phase, and Figure 3B is a partial circuit diagram showing the path of the DC current when the W phase is out of phase. [Figure 4] Figure 4A is a partial circuit diagram showing the path of the DC current when the U and V phases are out of phase, Figure 4B is a partial circuit diagram showing the path of the DC current when the V and W phases are out of phase, and Figure 4C is a partial circuit diagram showing the path of the DC current when the U and W phases are out of phase. [Figure 5] Figure 5 shows the voltage levels of the first signal, the second signal, and the third signal. [Figure 6] Figure 6A is a partial circuit diagram of the first comparative example, and Figure 6B is a partial circuit diagram of the second comparative example. [Figure 7] Figure 7A is a partial circuit diagram showing the path of the DC current in the normal state of the motor drive device according to the first modified example, and Figure 7B is a partial circuit diagram showing the path of the DC current when the U phase is out of phase. [Figure 8] Figure 8A is a partial circuit diagram showing the path of the DC current when the V phase is out of phase, and Figure 8B is a partial circuit diagram showing the path of the DC current when the W phase is out of phase. [Figure 9] Figure 9A is a partial circuit diagram showing the path of the DC current when the U and V phases are out of phase, Figure 9B is a partial circuit diagram showing the path of the DC current when the V and W phases are out of phase, and Figure 9C is a partial circuit diagram showing the path of the DC current when the U and W phases are out of phase. [Figure 10] Figure 10A is a partial circuit diagram showing the path of the DC current in the normal state of the motor drive device according to the second modified example, and Figure 10B is a partial circuit diagram showing the path of the DC current when the U phase is out of phase. [Figure 11] Figure 11A is a partial circuit diagram showing the path of the DC current when the V phase is out of phase, and Figure 11B is a partial circuit diagram showing the path of the DC current when the W phase is out of phase. [Figure 12] FIG. 12A is a partial circuit diagram showing the path of the direct current when the U-phase and V-phase are open-circuited, FIG. 12B is a partial circuit diagram showing the path of the direct current when the V-phase and W-phase are open-circuited, and FIG. 12C is a partial circuit diagram showing the path of the direct current when the U-phase and W-phase are open-circuited. [Figure 13] FIG. 13A is a partial circuit diagram showing the path of the direct current in the normal state of the motor driving device according to the third modification, and FIG. 13B is a partial circuit diagram showing the path of the direct current when the U-phase is open-circuited. [Figure 14] FIG. 14A is a partial circuit diagram showing the path of the direct current when the V-phase is open-circuited, and FIG. 14B is a partial circuit diagram showing the path of the direct current when the W-phase is open-circuited. <000682> [Figure 15] FIG. 15A is a partial circuit diagram showing the path of the direct current when the U-phase and V-phase are open-circuited, FIG. 15B is a partial circuit diagram showing the path of the direct current when the V-phase and W-phase are open-circuited, and FIG. 15C is a partial circuit diagram showing the path of the direct current when the U-phase and W-phase are open-circuited. MODE FOR CARRYING OUT THE INVENTION

[0010] It is not always easy to accurately detect an abnormality such as a disconnection in a drive circuit or the like for driving a three-phase motor. For example, it is not always easy to accurately detect in which phase a disconnection or the like has occurred.

[0011] [[ID=A]]

[0012] FIG. 1 is a circuit diagram of a motor driving device 10 according to an embodiment. The motor driving device 10 includes an inverter 12, a control device 14, a switching circuit 16, and an abnormality detection circuit 18. The motor driving device 10 can drive a three-phase motor 20.

[0013] The three-phase motor 20 is provided with three motor coils 22 (22U, 22V, 22W). That is, the three-phase motor 20 includes a motor coil 22U for the U phase (the first phase), a motor coil 22V for the V phase (the second phase), and a motor coil 22W for the W phase (the third phase). The three motor coils 22 are Y-connected. When generally describing the motor coil 22, the reference numeral 22 is used. When describing each individual motor coil 22, the reference numerals 22U, 22V, and 22W are used.

[0014] The three-phase motor 20 is further provided with a U-phase terminal (the first-phase terminal) 24U, a V-phase terminal (the second-phase terminal) 24V, and a W-phase terminal (the third-phase terminal) 24W. The motor coil 22U for the U phase is electrically connected to the U-phase terminal 24U. The motor coil 22V for the V phase is electrically connected to the V-phase terminal 24V. The motor coil 22W for the W phase is electrically connected to the W-phase terminal 24W.

[0015] [[ID=z]] The inverter 12 is electrically connected to the DC power supply 28 via a pair of DC power lines 26. One of the pair of DC power lines 26, the positive-side power line (the second power line) 26p, electrically connects the positive electrode of the DC power supply 28 and the inverter 12. The other of the pair of DC power lines 26, the negative-side power line (the first power line) 26n, electrically connects the negative electrode of the DC power supply 28 and the inverter 12. A capacitor 30 is electrically connected in parallel to the DC power supply 28.

[0016] The inverter 12 converts the DC voltage supplied from the DC power supply 28 via the DC power lines 26 into an AC voltage. The inverter 12 can drive the three-phase motor 20 by supplying the converted AC voltage to the three-phase motor 20.

[0017] As described above, the three-phase motor 20 is equipped with three motor coils 22. Therefore, the inverter 12 is equipped with three leg sections 32 (32U, 32V, 32W) corresponding to each phase of the three-phase motor 20. When describing the leg sections 32 in general, the reference numeral 32 is used. When describing the individual leg sections 32, the reference numerals 32U, 32V, and 32W are used.

[0018] The leg section 32 is equipped with an upper arm switching element 34u and a lower arm switching element 34d. When describing the switching element 34 in general, the reference numeral 34 is used. When describing individual switching elements 34, the reference numerals 34u and 34d are used. The switching element 34 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The leg section 32 is further equipped with an upper arm diode 36u and a lower arm diode 36d.

[0019] In the leg section 32, the switching element 34u of the upper arm and the switching element 34d of the lower arm are connected in series with each other. The diode 36u of the upper arm is connected in parallel with the switching element 34u of the upper arm. The diode 36d of the lower arm is connected in parallel with the switching element 34d of the lower arm.

[0020] The first terminal of the upper arm switching element 34u is connected to the positive power supply line 26p. The cathode of the upper arm diode 36u is connected to the first terminal. The first terminal is either the source or the drain. The second terminal of the upper arm switching element 34u is connected to the anode of the upper arm diode 36u. The second terminal is either the source or the drain.

[0021] The cathode of the diode 36u on the lower arm is connected to the first terminal of the switching element 34d on the lower arm. The second terminal of the switching element 34d on the lower arm is connected to the negative side power supply line 26n. The anode of the diode 36u on the lower arm is connected to the second terminal.

[0022] The second terminal of the switching element 34u on the upper arm, the anode of the diode 36u on the upper arm, the first terminal of the switching element 34d on the lower arm, and the cathode of the diode 36u on the lower arm are connected to node 38 (38U, 38V, 38W).

[0023] The three leg sections 32U, 32V, and 32W are connected to the respective phases of the three-phase motor 20. Specifically, node 38U of leg section 32U is connected to the U-phase terminal 24U via wiring 40U. Node 38V of leg section 32V is connected to the V-phase terminal 24V via wiring 40V. Node 38W of leg section 32W is connected to the W-phase terminal 24W via wiring 40W. Wirings 40U, 40V, and 40W for each phase are used to supply three-phase AC voltage from the inverter 12 to the three-phase motor 20.

[0024] Note that the switching element 34 is not limited to a MOSFET. A FET or IGBT (Insulated Gate Bipolar Transistor) may also be used as the switching element 34.

[0025] The switching circuit 16 controls the switching of the switching element 34 provided in the inverter 12. Based on a signal (command) supplied from the control device 14, the switching circuit 16 switches the switching element 34 by applying a voltage to the third terminal (gate) of the switching element 34. The inverter 12 drives the three-phase motor 20 by appropriately switching the switching element 34u of the upper arm and the switching element 34d of the lower arm to convert the DC voltage into AC voltage.

[0026] The abnormality detection circuit 18 can detect the presence or absence of an abnormality. Examples of abnormalities include phase loss due to a broken wire.

[0027] The abnormality detection circuit 18 includes a first conduction path 42U, a second conduction path 42V, a third conduction path 42W, a fourth conduction path 44, a resistor circuit 46, a first electrical resistor 48U, a second electrical resistor 48V, a third electrical resistor 48W, a fourth electrical resistor 50, a fifth electrical resistor 52U, a sixth electrical resistor 52V, a seventh electrical resistor 52W, an eighth electrical resistor 54U, a ninth electrical resistor 54V, a tenth electrical resistor 54W, and an output circuit 56.

[0028] The first conduction path 42U is a wiring that connects the U-phase terminal 24U to the negative-side power supply line 26n. One end of the first conduction path 42U is connected to the U-phase terminal 24U. The other end of the first conduction path 42U is connected to the negative-side power supply line 26n.

[0029] The second conduction path 42V is a wiring that connects the V-phase terminal 24V to the negative-side power supply line 26n. One end of the second conduction path 42V is connected to the V-phase terminal 24V. The other end of the second conduction path 42V is connected to the negative-side power supply line 26n.

[0030] The third conductive path 42W is a wiring that connects the W-phase terminal 24W to the negative-side power supply line 26n. One end of the third conductive path 42W is connected to the W-phase terminal 24W. The other end of the third conductive path 42W is connected to the negative-side power supply line 26n.

[0031] The fourth conduction path 44 is a wiring that connects the U-phase terminal 24U to the positive-side power supply line 26p. One end of the fourth conduction path 44 is connected to the U-phase terminal 24U. The other end of the fourth conduction path 44 is connected to the positive-side power supply line 26p. The fourth conduction path 44 is provided with a fourth electrical resistor 50.

[0032] Note that the fourth conduction path 44 is not limited to being connected to the U-phase terminal 24U. The fourth conduction path 44 may also be connected to the V-phase terminal 24V or the W-phase terminal 24W. When the fourth conduction path 44 is connected to the V-phase terminal 24V, the fourth conduction path 44 is not connected to either the U-phase terminal 24U or the W-phase terminal 24W. When the fourth conduction path 44 is connected to the W-phase terminal 24W, the fourth conduction path 44 is not connected to either the U-phase terminal 24U or the V-phase terminal 24V.

[0033] The resistor circuit 46 is Y-connected and electrically connected to the first conduction path 42U, the second conduction path 42V, and the third conduction path 42W. Specifically, the resistor circuit 46 comprises three electrical resistors 58 (eleventh electrical resistor 58U, twelfth electrical resistor 58V, and thirteenth electrical resistor 58W). The three electrical resistors 58 are Y-connected; that is, one end of each of the three electrical resistors 58 is connected to the others. The other end of the eleventh electrical resistor 58U is electrically connected to the first conduction path 42U. The other end of the twelfth electrical resistor 58V is electrically connected to the second conduction path 42V. The other end of the thirteenth electrical resistor 58W is electrically connected to the third conduction path 42W.

[0034] The three electrical resistors 58 have the same resistance value. That is, the resistance value R11 of the 11th electrical resistor 58U, the resistance value R12 of the 12th electrical resistor 58V, and the resistance value R13 of the 13th electrical resistor 58W are all the same (R11=R12=R13).

[0035] The first conduction path 42U has a first partial path 42Ud. The first partial path 42Ud is the portion of the first conduction path 42U located between the resistor circuit 46 and the negative terminal power line 26n. The first partial path 42Ud is provided with a first electrical resistor 48U.

[0036] The second conducting path 42V has a second sub-path 42Vd. The second sub-path 42Vd is the portion of the second conducting path 42V located between the resistor circuit 46 and the negative terminal power line 26n. The second sub-path 42Vd is provided with a second electrical resistor 48V.

[0037] The third conductive path 42W has a third sub-path 42Wd. The third sub-path 42Wd is the portion of the third conductive path 42W located between the resistor circuit 46 and the negative terminal power line 26n. The third sub-path 42Wd is provided with a third electrical resistor 48W.

[0038] The resistance value R1 of the first electrical resistance 48U, the resistance value R2 of the second electrical resistance 48V, and the resistance value R3 of the third electrical resistance 48W are all equal in magnitude (R1=R2=R3).

[0039] The fifth electrical resistor 52U is provided in the first subpath 42Ud. The fifth electrical resistor 52U is located between the first electrical resistor 48U and the resistor circuit 46 in the first subpath 42Ud.

[0040] The sixth electrical resistor 52V is provided in the second sub-path 42Vd. The sixth electrical resistor 52V is located between the second electrical resistor 48V and the resistor circuit 46 in the second sub-path 42Vd.

[0041] The seventh electrical resistor 52W is provided in the third sub-path 42Wd. The seventh electrical resistor 52W is located between the third electrical resistor 48W and the resistor circuit 46 in the third sub-path 42Wd.

[0042] The resistance values ​​R5 of the 5th electrical resistor 52U, R6 of the 6th electrical resistor 52V, and R7 of the 7th electrical resistor 52W are all equal in magnitude (R5=R6=R7). The resistance values ​​R5 of the 5th electrical resistor 52U, R6 of the 6th electrical resistor 52V, and R7 of the 7th electrical resistor 52W are greater than the resistance values ​​R1 of the 1st electrical resistor 48U, R2 of the 2nd electrical resistor 48V, and R3 of the 3rd electrical resistor 48W (R5=R6=R7, R1=R2=R3, R5>R1, R6>R2, R7>R3).

[0043] The first conduction path 42U further has a fourth sub-path 42Uu. The fourth sub-path 42Uu is the portion of the first conduction path 42U located between the resistor circuit 46 and the U-phase terminal 24U. The fourth sub-path 42Uu is provided with an eighth electrical resistor 54U.

[0044] The second conducting path 42V further has a fifth sub-path 42Vu. The fifth sub-path 42Vu is the portion of the second conducting path 42V located between the resistor circuit 46 and the V-phase terminal 24V. The fifth sub-path 42Vu is provided with a ninth electrical resistor 54V.

[0045] The third conducting path 42W further has a sixth sub-path 42Wu. The sixth sub-path 42Wu is the portion of the third conducting path 42W located between the resistor circuit 46 and the W-phase terminal 24W. The sixth sub-path 42Wu is provided with a tenth electrical resistor 54W.

[0046] The resistance values ​​R8 of the 8th electrical resistor 54U, R9 of the 9th electrical resistor 54V, and R10 of the 10th electrical resistor 54W are all equal in magnitude (R8=R9=R10). The resistance values ​​R8 of the 8th electrical resistor 54U, R9 of the 9th electrical resistor 54V, and R10 of the 10th electrical resistor 54W are greater than the resistance values ​​R5 of the 5th electrical resistor 52U, R6 of the 6th electrical resistor 52V, and R7 of the 7th electrical resistor 52W (R8=R9=R10, R5=R6=R7, R8>R5, R9>R6, R10>R7).

[0047] The output circuit 56 has three wires 56U, 56V, and 56W. Wire 56U connects the portion of the first subpath 42Ud between the first electrical resistor 48U and the fifth electrical resistor 52U to the control device 14. Wire 56V connects the portion of the second subpath 42Vd between the second electrical resistor 48V and the sixth electrical resistor 52V to the control device 14. Wire 56W connects the portion of the third subpath 42Wd between the third electrical resistor 48W and the seventh electrical resistor 52W to the control device 14.

[0048] The determination of whether or not there is an abnormality (abnormality detection) is performed with the inverter 12 turned off. When an abnormality is detected, a DC voltage is supplied from the DC power supply 28 to the abnormality detection circuit 18. The output circuit 56 outputs at least one of the first signal S1, the second signal S2, and the third signal S3 to the control device 14.

[0049] The first signal S1 is a signal corresponding to the first current I1, which is the DC current flowing through the first electrical resistor 48U. The output circuit 56 can output the first signal S1 to the control device 14 via the wiring 56U.

[0050] The second signal S2 is a signal corresponding to the second current I2, which is the DC current flowing through the second electrical resistor 48V. The output circuit 56 can output the second signal S2 to the control device 14 via the wiring 56V.

[0051] The third signal S3 is a signal corresponding to the third current I3, which is the DC current flowing through the third electrical resistor 48W. The output circuit 56 can output the third signal S3 to the control device 14 via the wiring 56W.

[0052] The output circuit 56 outputs at least one of the second signal S2 and the third signal S3. The output circuit 56 may output either the second signal S2 or the third signal S3 and the first signal S1. The output circuit 56 may output any of the first signal S1, the second signal S2, and the third signal S3.

[0053] The control device 14 is responsible for the overall control of the motor drive device 10. The control device 14 is equipped with an arithmetic unit 14a and a storage unit 14b. The arithmetic unit 14a may be composed of a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). In other words, the arithmetic unit 14a may be composed of processing circuitry. The arithmetic unit 14a is equipped with a control unit 60 and a determination unit 62. The control unit 60 and the determination unit 62 may be realized by the execution of a program stored in the storage unit 14b by the arithmetic unit 14a.

[0054] Furthermore, at least a portion of the control unit 60 and the determination unit 62 may be implemented by integrated circuits such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field-Programmable Gate Arrays). Also, at least a portion of the control unit 60 and the determination unit 62 may be composed of electronic circuits including discrete devices.

[0055] The storage unit 14b may consist of a volatile memory (not shown) and a non-volatile memory (not shown). Examples of volatile memory include RAM (Random Access Memory). This volatile memory is used as the working memory of the processor and temporarily stores data necessary for processing or calculations. Examples of non-volatile memory include ROM (Read Only Memory) and flash memory. This non-volatile memory is used as storage memory and stores programs, tables, maps, etc. At least a part of the storage unit 14b may be provided in the processor, integrated circuit, etc. as described above.

[0056] The control unit 60 can switch the switching elements 34 using the switching circuit 16. When an abnormality is detected, the control unit 60 turns off the inverter 12. That is, when an abnormality is detected, the control unit 60 turns off all the switching elements 34.

[0057] The determination unit 62 performs an abnormality determination based on the signals input to the control device 14 from the output circuit 56 (at least one of the first signal S1, the second signal S2, and the third signal S3). Specifically, the determination unit 62 determines whether or not there is a phase loss due to a broken wire or the like, based on the signals input to the control device 14 from the output circuit 56. Details of the determination process will be described later.

[0058] The abnormality detection by the abnormality detection circuit 18 will be explained with reference to Figures 2A to 5.

[0059] Figure 2A is a partial circuit diagram showing the path of DC current when each phase is in a normal state. In Figure 2A, only the three-phase motor 20 and the abnormality detection circuit 18 of the motor drive unit 10 (see Figure 1) are shown. In a normal state, no phase loss due to wire breakage or other reasons occurs.

[0060] As described above, when an abnormality is detected, a DC voltage is supplied from the DC power supply 28 to the abnormality detection circuit 18. In the normal state, a DC current flows through the three-phase motor 20 and the abnormality detection circuit 18 in the direction indicated by the arrows in Figure 2A.

[0061] As described above, R1=R2=R3, R5=R6=R7, R8=R9=R10, and R11=R12=R13. Also, the electrical resistances of the motor coils 22 in each phase are equal to each other. As a result, the other ends of the three electrical resistors 58 (11th electrical resistor 58U, 12th electrical resistor 58V, 13th electrical resistor 58W) of the resistor circuit 46 are at the same potential.

[0062] DC current flows from the positive power line 26p through the fourth conduction path 44 to the first conduction path 42U. DC current flows from the positive power line 26p through the fourth conduction path 44 and through the U-phase motor coil 22U and the V-phase motor coil 22V to the second conduction path 42V. DC current flows from the positive power line 26p through the fourth conduction path 44 and through the U-phase motor coil 22U and the W-phase motor coil 22W to the third conduction path 42W. No DC current flows through the resistor circuit 46. DC current of the same magnitude flows through the first conduction path 42U, the second conduction path 42V, and the third conduction path 42W.

[0063] The output circuit 56 (see Figure 1) outputs a voltage signal corresponding to the first current I1, which is the DC current flowing through the first electrical resistor 48U, as the first signal S1 to the control device 14. The output circuit 56 outputs a voltage signal corresponding to the second current I2, which is the DC current flowing through the second electrical resistor 48V, as the second signal S2 to the control device 14. The output circuit 56 outputs a voltage signal corresponding to the third current I3, which is the DC current flowing through the third electrical resistor 48W, as the third signal S3 to the control device 14.

[0064] Figure 5 shows the first signal S1, second signal S2, and third signal S3 in a normal state, illustrated with solid lines. The resistance values ​​R1 of the first electrical resistor 48U (see Figure 2A), R2 of the second electrical resistor 48V, and R3 of the third electrical resistor 48W are all the same magnitude, and the first current I1, second current I2, and third current I3 are all the same magnitude. Therefore, the signal levels (voltage values ​​Vn) of the first signal S1, second signal S2, and third signal S3 are all the same magnitude.

[0065] Figure 2B is a partial circuit diagram showing the case when the U phase is out of phase. The U phase is out of phase, for example, by a break in the wire between the fourth conduction path 44 and the U phase terminal 24U. When a DC voltage is supplied from the DC power supply 28 (see Figure 1) to the abnormality detection circuit 18 while the U phase is out of phase, a DC current flows in the direction indicated by the arrow in Figure 2B.

[0066] Since a break in the wire has occurred between the fourth conduction path 44 and the U-phase terminal 24U, no DC current flows through the three-phase motor 20. DC current flows through the second conduction path 42V and the third conduction path 42W via the fourth sub-path 42Uu and the resistor circuit 46. Specifically, DC current flows through the second sub-path 42Vd via the fourth sub-path 42Uu, the eleventh electrical resistor 58U, and the twelfth electrical resistor 58V. DC current flows through the third sub-path 42Wd via the fourth sub-path 42Uu, the eleventh electrical resistor 58U, and the thirteenth electrical resistor 58W. In other words, the DC current that flows into the 11th electrical resistor 58U is divided into a DC current (second current I2) that flows through the 12th electrical resistor 58V into the second conduction path 42V, and a DC current (third current I3) that flows through the 13th electrical resistor 58W into the third conduction path 42W.

[0067] Figure 5 shows the signal levels of the first signal S1, second signal S2, and third signal S3 when the U phase is missing, illustrated with dashed lines. When the U phase is missing, the signal level (voltage value Vf4) of the first signal S1 is greater than the signal levels (voltage value Vn) of the first signal S1, second signal S2, and third signal S3 under normal conditions (Vf4>Vn). Also, when the U phase is missing, the signal levels (voltage value Vf1) of the second signal S2 and third signal S3 are the same magnitude. When the U phase is missing, the signal levels of the second signal S2 and third signal S3 are smaller than the signal level of the first signal S1 when the U phase is missing, and also smaller than the signal levels of the first signal S1, second signal S2, and third signal S3 under normal conditions (Vf4>Vn>Vf1).

[0068] Figure 3A is a partial circuit diagram showing the case when the V phase is out of phase. The V phase is out of phase, for example, by a break in the wire between the second conduction path 42V and the V phase terminal 24V. When the V phase is out of phase, if a DC voltage is supplied from the DC power supply 28 (see Figure 1) to the abnormality detection circuit 18, a DC current flows in the direction indicated by the arrow in Figure 3A.

[0069] Since a break in the circuit has occurred between the second conduction path 42V and the V-phase terminal 24V, no DC current flows from the V-phase motor coil 22V to the second conduction path 42V. Therefore, a DC current flows through the second sub-path 42Vd from the fourth sub-path 42Uu via the resistor circuit 46, and a DC current also flows through the sixth sub-path 42Wu via the resistor circuit 46. Specifically, a DC current flows through the second sub-path 42Vd via the fourth sub-path 42Uu, the eleventh electrical resistor 58U, and the twelfth electrical resistor 58V. In addition, a DC current flows through the second sub-path 42Vd via the sixth sub-path 42Wu, the thirteenth electrical resistor 58W, and the twelfth electrical resistor 58V. In other words, a portion of the DC current flowing through the fourth subpath 42Uu and a portion of the DC current flowing through the sixth subpath 42Wu flow into the twelfth electrical resistor 58V and then into the second subpath 42Vd.

[0070] Figure 5 shows the first signal S1, second signal S2, and third signal S3 when the V phase is missing, illustrated by dashed lines. When the V phase is missing, the signal levels (voltage values ​​Vf3) of the first signal S1 and third signal S3 are greater than the signal levels (voltage values ​​Vn) of the first signal S1 and third signal S3 under normal conditions (Vf3>Vn). Also, when the V phase is missing, the signal level (voltage value Vf3) of the first signal S1 is less than the signal level (voltage value Vf4) of the first signal S1 when the U phase is missing (Vf4>Vf3). Furthermore, when the V phase is missing, the signal level (voltage value Vf2) of the second signal S2 is less than the signal level (voltage value Vn) of the second signal S2 under normal conditions, and greater than the signal level (voltage value Vf1) of the second signal S2 when the U phase is missing (Vn>Vf2>Vf1).

[0071] Figure 3B is a partial circuit diagram showing the case when the W phase is out of phase. The W phase is out of phase, for example, by a break in the wire between the third conduction path 42W and the W phase terminal 24W. When the W phase is out of phase, if a DC voltage is supplied from the DC power supply 28 (see Figure 1) to the abnormality detection circuit 18, a DC current flows in the direction indicated by the arrow in Figure 3B.

[0072] Since a break in the circuit has occurred between the third conduction path 42W and the W-phase terminal 24W, no DC current flows from the W-phase motor coil 22W to the third conduction path 42W. Therefore, DC current flows through the third sub-path 42Wd from the fourth sub-path 42Uu via the resistor circuit 46, and also from the fifth sub-path 42Vu via the resistor circuit 46. Specifically, DC current flows through the third sub-path 42Wd via the fourth sub-path 42Uu, the eleventh electrical resistor 58U, and the thirteenth electrical resistor 58W. In addition, DC current flows through the third sub-path 42Wd via the fifth sub-path 42Vu, the twelfth electrical resistor 58V, and the thirteenth electrical resistor 58W. In other words, a portion of the DC current flowing through the fourth subpath 42Uu and a portion of the DC current flowing through the fifth subpath 42Vu flow into the 13th electrical resistor 58W and then flow into the third subpath 42Wd.

[0073] Figure 5 shows the first signal S1, second signal S2, and third signal S3 when the W phase is missing, illustrated with dashed lines. When the W phase is missing, the signal levels (voltage values ​​Vf3) of the first signal S1 and second signal S2 are greater than the signal levels (voltage values ​​Vn) of the first signal S1 and second signal S2 under normal conditions (Vf3>Vn). Also, when the W phase is missing, the signal level (voltage value Vf3) of the first signal S1 is less than the signal level (voltage value Vf4) of the first signal S1 when the U phase is missing (Vf4>Vf3). Furthermore, when the W phase is missing, the signal level (voltage value Vf2) of the third signal S3 is less than the signal level (voltage value Vn) of the third signal S3 under normal conditions, and greater than the signal level (voltage value Vf1) of the third signal S3 when the U phase is missing (Vn>Vf2>Vf1).

[0074] Figures 4A to 4C are partial circuit diagrams showing the case when two phases are lost. Two-phase loss occurs, for example, due to a break in the wiring between the terminals of the two phases and the conductive path connected to those terminals. When two phases are lost, if a DC voltage is supplied from the DC power supply 28 (see Figure 1) to the abnormality detection circuit 18, a DC current flows in the direction indicated by the arrows in Figures 4A to 4C.

[0075] Figure 4A is a partial circuit diagram when two phases, the U phase and the V phase, are out of phase. In Figure 4A, a break in the circuit occurs between the fourth conduction path 44 and the U phase terminal 24U, so no DC current flows through the three-phase motor 20.

[0076] Figure 4B is a partial circuit diagram when two phases, the V phase and the W phase, are out of phase. In Figure 4B, a break in the circuit occurs between the second conduction path 42V and the V phase terminal 24V, and also between the third conduction path 42W and the W phase terminal 24W, so no DC current flows through the three-phase motor 20.

[0077] Figure 4C is a partial circuit diagram when two phases, the U phase and the W phase, are out of phase. In Figure 4C, a break in the circuit occurs between the fourth conduction path 44 and the U phase terminal 24U, so no DC current flows through the three-phase motor 20.

[0078] Thus, when two phases are out of phase, no DC current flows through the three-phase motor 20. Therefore, the path of the DC current when two phases are out of phase is the same as the path of the DC current when only the U phase is out of phase (see Figure 2B). Consequently, as shown by the dashed line in Figure 5, the signal level (voltage value Vf4) of the first signal S1 when two phases are out of phase is the same magnitude as the signal level (voltage value Vf4) of the first signal S1 when only the U phase is out of phase. Also, the signal level (voltage value Vf1) of the second signal S2 when two phases are out is the same magnitude as the signal level (voltage value Vf1) of the second signal S2 when only the U phase is out of phase. The signal level (voltage value Vf1) of the third signal S3 when two phases are out is the same magnitude as the signal level (voltage value Vf1) of the third signal S3 when only the U phase is out of phase.

[0079] Figure 5 shows the signal levels (voltage values ​​Vf0) of the first signal S1, second signal S2, and third signal S3 when each phase of the three-phase motor 20 (see Figure 1) is ground faulted, illustrated by dashed lines. When each phase is ground faulted, the signal levels (voltage values ​​Vf0) of the first signal S1, second signal S2, and third signal S3 become 0 (Vf0=0).

[0080] Furthermore, Figure 5 shows the signal levels (voltage values ​​Vf5) of the first signal S1, second signal S2, and third signal S3 when each phase of the three-phase motor 20 (see Figure 1) is short-circuited (overhead fault) to the positive terminal of the DC power supply 28, with solid lines illustrating the signal levels (voltage values ​​Vf5) of the first signal S1, second signal S2, and third signal S3. When each phase is overhead, the signal levels (voltage values ​​Vf5) of the first signal S1, second signal S2, and third signal S3 will be in proportion to the voltage of the DC power supply 28.

[0081] The memory unit 14b (see Figure 1) may store a table containing the signal levels of the first signal S1, second signal S2, and third signal S3 in the normal state, the state of phase loss in each phase, the state of two-phase phase loss, the state of a ground fault, and the state of an air fault. When an abnormality is detected, the determination unit 62 compares the signal levels of the signals (first signal S1, second signal S2, third signal S3) input from the output circuit 56 to the control device 14 with the signal levels stored in the table to determine whether or not there is a phase loss or the like. The determination unit 62 may notify the outside of the determination result via a notification device (not shown). Examples of notification devices include a display device such as a display and a sound output device such as a speaker.

[0082] Figure 6A is a partial circuit diagram of the first comparative example. Figure 6B is a partial circuit diagram of the second comparative example. In the first and second comparative examples, the same components as those in the motor drive device 10 (see Figure 1) according to one embodiment are described using the same reference numerals.

[0083] In the first comparative example shown in Figure 6A, the terminals of each phase of the three-phase motor 20 are connected to the positive-side power supply line 26p via an electrical resistor 70. Also, in the first comparative example, the resistor circuit 46 (see Figure 1) is not provided. In the first comparative example, regardless of whether there is a phase loss or not, the same magnitude of DC current flows through the first conduction path 42U, the second conduction path 42V, and the third conduction path 42W. Therefore, the signal levels of the first signal S1, second signal S2, and third signal S3 in a normal state are the same as the signal levels of the first signal S1, second signal S2, and third signal S3 when a phase loss occurs. In other words, it is not possible to determine whether there is a phase loss or not in the first comparative example.

[0084] Figure 6B is a partial circuit diagram of the second comparative example. In the second comparative example, the resistor circuit 46 (see Figure 1) is not provided. In the second comparative example, it is possible to determine that at least one phase is out of phase. However, in the second comparative example, it is not possible to distinguish between a single-phase outage and a two-phase outage.

[0085] In contrast, in the motor drive device 10 according to one embodiment (see Figure 1), as shown in Figure 5, a first signal S1, a second signal S2, and a third signal S3 are obtained, each with a signal level corresponding to the type of phase loss. In particular, in the second signal S2, the signal levels for U-phase phase loss, V-phase phase loss, and W-phase phase loss are different from each other. Similarly, in the third signal S3, the signal levels for U-phase phase loss, V-phase phase loss, and W-phase phase loss are different from each other. Therefore, the determination unit 62 can easily identify which phase has a phase loss based on only one of the second signal S2 and the third signal S3. In other words, abnormalities such as wire breaks can be accurately identified based on only one signal.

[0086] Furthermore, in the second signal S2, the signal level differs depending on whether the V phase or W phase is missing or whether two phases of each phase are missing. Similarly, in the third signal S3, the signal level differs depending on whether the V phase or W phase is missing or whether two phases of each phase are missing. As a result, the determination unit 62 can distinguish between a single phase loss and a two-phase loss based on the signal level of at least one of the second signal S2 and the third signal S3.

[0087] Furthermore, with respect to the first signal S1, the signal level when a phase loss occurs is higher than the signal level when a normal phase loss occurs. In contrast, with respect to the second signal S2 and the third signal S3, except in some cases of phase loss, the signal level when a phase loss occurs is lower than the signal level when a normal phase loss occurs. As a result, by inputting the first signal S1 and the second signal S2 or the third signal S3 to the control device 14, and having the determination unit 62 perform an abnormality determination based on the first signal and the second signal S2 or the third signal S3, the accuracy of the abnormality determination can be effectively improved.

[0088] Figures 7A to 9C are partial circuit diagrams of a first modified example of the motor drive device 10 (see Figure 1). In the first modified example, the resistor circuit 46 is delta-connected. In the first modified example, the paths of the DC current are illustrated in Figures 7A to 9C, and a detailed explanation is omitted. Figure 7A illustrates the path of the DC current when the system is functioning normally. Figure 7B illustrates the path of the DC current when the U phase is out of phase. Figure 8A illustrates the path of the DC current when the V phase is out of phase. Figure 8B illustrates the path of the DC current when the W phase is out of phase. Figure 9A illustrates the paths of the DC current when both the U and V phases are out of phase. Figure 9B illustrates the paths of the DC current when both the V and W phases are out of phase. Figure 9C illustrates the paths of the DC current when both the U and W phases are out of phase.

[0089] Figures 10A to 12C are partial circuit diagrams of a second modified version of the motor drive device 10 (see Figure 1). In the second modified version, the three-phase motor 20 and the resistor circuit 46 are each delta-connected. In the second modified version, the paths of the DC current are illustrated in Figures 10A to 12C, and a detailed explanation is omitted. Figure 10A illustrates the path of the DC current when the system is functioning normally. Figure 10B illustrates the path of the DC current when the U phase is out of phase. Figure 11A illustrates the path of the DC current when the V phase is out of phase. Figure 11B illustrates the path of the DC current when the W phase is out of phase. Figure 12A illustrates the path of the DC current when the U phase and V phase are out of phase. Figure 12B illustrates the path of the DC current when the V phase and W phase are out of phase. Figure 12C illustrates the path of the DC current when the U phase and W phase are out of phase.

[0090] Figures 13A to 15C are partial circuit diagrams of a third modified example of the motor drive device 10 (see Figure 1). In the third modified example, the three-phase motor 20 is delta-connected. In the third modified example, the paths of the DC current are illustrated in Figures 13A to 15C, and a detailed explanation is omitted. Figure 13A illustrates the path of the DC current when the system is functioning normally. Figure 13B illustrates the path of the DC current when the U phase is out of phase. Figure 14A illustrates the path of the DC current when the V phase is out of phase. Figure 14B illustrates the path of the DC current when the W phase is out of phase. Figure 15A illustrates the path of the DC current when the U phase and V phase are out of phase. Figure 15B illustrates the path of the DC current when the V phase and W phase are out of phase. Figure 15C illustrates the path of the DC current when the U phase and W phase are out of phase.

[0091] The following additional information is disclosed regarding the above embodiments.

[0092] (Note 1) The abnormality detection circuit (18) of this disclosure includes: a first conduction path (42U) that conducts a first phase terminal (24U) provided on a three-phase motor (20) to a first power line (26n), which is one of a pair of DC power lines (26); a second conduction path (42V) that conducts a second phase terminal (24V) provided on the three-phase motor to the first power line; a third conduction path (42W) that conducts a third phase terminal (24W) provided on the three-phase motor to the first power line; a resistor circuit (46) that is Δ-connected or Y-connected and electrically connected to the first conduction path, the second conduction path, and the third conduction path; a first electrical resistor (48U) provided on a first partial path (42Ud), which is the portion of the first conduction path located between the resistor circuit and the first power line; and the resistor circuit and the first electrical resistor in the second conduction path. The circuit includes a second electrical resistor (48V) provided in a second partial path (42Vd) located between the power line and the circuit, a third electrical resistor (48W) provided in a third partial path (42Wd) located between the resistor circuit and the first power line of the third conduction path, a fourth electrical resistor (50) provided in a fourth conduction path (44) that conducts one of the first phase terminal, the second phase terminal and the third phase terminal to the second power line (26p), which is the other of the pair of DC power lines, and an output circuit (56) that outputs at least one of the following signals: a first signal (S1) corresponding to the current flowing through the first electrical resistor, a second signal (S2) corresponding to the current flowing through the second electrical resistor, and a third signal (S3) corresponding to the current flowing through the third electrical resistor.

[0093] This configuration provides a first signal, a second signal, and a third signal with signal levels corresponding to the type of phase loss. Based on the signal level of one signal, it is possible to identify which phase is experiencing the abnormality. In other words, abnormalities such as wire breaks can be accurately identified based on only one signal.

[0094] (Note 2) In the abnormality detection circuit described in Appendix 1, the fourth conductive path may connect the first phase terminal and the second power line, and the output circuit may output the second signal or the third signal.

[0095] This configuration allows for effective identification of single-phase and two-phase phase loss based on the signal levels of the second or third signal.

[0096] (Note 3) In the abnormality detection circuit described in Appendix 2, the output circuit may further output the first signal.

[0097] This configuration effectively improves the accuracy of anomaly detection.

[0098] (Note 4) In the abnormality detection circuit described in Appendix 1, the three electrical resistors (58) provided in the resistor circuit may have the same resistance value (R11, R12, R13).

[0099] This configuration allows for effectively differentiating the signal levels of the first, second, and third signals when a phase loss occurs.

[0100] (Note 5) In the abnormality detection circuit described in Appendix 1, the first electrical resistor, the second electrical resistor, and the third electrical resistor may have the same resistance value (R1, R2, R3).

[0101] This configuration makes it possible to make the signal levels of the first signal, the second signal, and the third signal the same when everything is functioning normally.

[0102] (Note 6) The abnormality detection circuit described in Appendix 5 further comprises a fifth electrical resistor (52U) provided in the first partial path and located between the first electrical resistor and the resistance circuit, a sixth electrical resistor (52V) provided in the second partial path and located between the second electrical resistor and the resistance circuit, and a seventh electrical resistor (52W) provided in the third partial path and located between the third electrical resistor and the resistance circuit, wherein the fifth electrical resistor, the sixth electrical resistor and the seventh electrical resistor have the same resistance value (R5, R6, R7), and the resistance values ​​of the fifth electrical resistor, the sixth electrical resistor and the seventh electrical resistor may be higher than the resistance values ​​of the first electrical resistor, the second electrical resistor and the third electrical resistor.

[0103] (Note 7) The abnormality detection circuit described in Appendix 6 further includes an eighth electrical resistor (54U) provided in the fourth sub-path (42Uu), which is the portion of the first conduction path located between the resistor circuit and the first phase terminal; a ninth electrical resistor (54V) provided in the fifth sub-path (42Vu), which is the portion of the second conduction path located between the resistor circuit and the second phase terminal; and a tenth electrical resistor (54W) provided in the sixth sub-path (42Wu), which is the portion of the third conduction path located between the resistor circuit and the third phase terminal, wherein the eighth, ninth, and tenth electrical resistors may have the same resistance value (R8, R9, R10).

[0104] (Note 8) In the abnormality detection circuit described in Appendix 7, the resistance values ​​of the eighth electrical resistance, the ninth electrical resistance, and the tenth electrical resistance may be higher than the resistance values ​​of the fifth electrical resistance, the sixth electrical resistance, and the seventh electrical resistance.

[0105] (Note 9) The motor drive device (10) of this disclosure comprises the abnormality detection circuit described in any one of appendices 1 to 8, an inverter (12) for driving the three-phase motor, and a determination unit (62) that performs abnormality determination based on the signal output from the abnormality detection circuit, wherein the determination unit performs the abnormality determination with the inverter turned off.

[0106] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols]

[0107] 10…Motor drive unit 12…Inverter 18…Anomaly detection circuit 20…Three-phase motor 24U…U-phase terminal (1st phase terminal) 24V…V-phase terminal (2nd phase terminal) 24W…W-phase terminal (3rd phase terminal) 26…DC power line 26n…Negative side power line (1st power line) 26p…Positive side power line (2nd power line) 42U…1st continuity path 42Ud…1st partial path 42V…2nd continuity path 42Vd…2nd partial path 42W…3rd continuity path 42Wd…3rd partial path 44…4th continuity path 46…Resistance circuit 48U…1st electrical resistance 48V…2nd electrical resistance 48W…3rd electrical resistance 50…4th electrical resistance 56…Output circuit 62…Determination unit S1…1st signal S2…2nd signal S3...Third signal

Claims

1. A first conductive path connects the first phase terminal of a three-phase motor to the first power line, which is one of a pair of DC power lines. A second conductive path that connects the second phase terminal of the three-phase motor to the first power line, A third conductive path that connects the third phase terminal of the three-phase motor to the first power line, A resistive circuit that is Δ-connected or Y-connected and electrically connected to the first conduction path, the second conduction path, and the third conduction path, A first electrical resistor is provided in the first partial path, which is the portion of the first conductive path located between the resistor circuit and the first power line, A second electrical resistor is provided in the second partial path, which is the portion of the second conductive path located between the resistor circuit and the first power line, A third electrical resistor is provided in the third partial path, which is the portion of the third conductive path located between the resistor circuit and the first power line, A fourth electrical resistor is provided, and a fourth conductive path is provided that connects one of the first phase terminal, the second phase terminal, and the third phase terminal to the second power line, which is the other of the pair of DC power lines. An output circuit that outputs at least one of the following signals: a first signal which corresponds to the current flowing through the first electrical resistor, a second signal which corresponds to the current flowing through the second electrical resistor, and a third signal which corresponds to the current flowing through the third electrical resistor. An anomaly detection circuit equipped with this.

2. In the abnormality detection circuit according to claim 1, The fourth conductive path connects the first phase terminal and the second power line, The output circuit is an abnormality detection circuit that outputs the second signal or the third signal.

3. In the abnormality detection circuit according to claim 2, The output circuit is an abnormality detection circuit that further outputs the first signal.

4. In the abnormality detection circuit according to claim 1, The three electrical resistors in the aforementioned resistor circuit have the same resistance value, forming an abnormality detection circuit.

5. In the abnormality detection circuit according to claim 1, An abnormality detection circuit in which the first electrical resistor, the second electrical resistor, and the third electrical resistor have the same resistance value.

6. In the abnormality detection circuit according to claim 5, A fifth electrical resistor is provided in the first partial path and is located between the first electrical resistor and the resistor circuit, A sixth electrical resistor is provided in the second partial path and is located between the second electrical resistor and the resistor circuit, A seventh electrical resistor is provided in the third partial path and is located between the third electrical resistor and the resistor circuit, Furthermore, The fifth electrical resistance, the sixth electrical resistance, and the seventh electrical resistance have the same resistance value to each other. An abnormality detection circuit in which the resistance values ​​of the fifth, sixth, and seventh electrical resistances are higher than the resistance values ​​of the first, second, and third electrical resistances.

7. In the abnormality detection circuit according to claim 6, An eighth electrical resistor is provided in the fourth sub-path, which is the portion of the first conduction path located between the resistor circuit and the first phase terminal, A ninth electrical resistor is provided in the fifth sub-path, which is the portion of the second conduction path located between the resistor circuit and the second phase terminal, A tenth electrical resistor is provided in the sixth sub-path, which is the portion of the third conduction path located between the resistor circuit and the third phase terminal, Furthermore, An abnormality detection circuit in which the eighth electrical resistor, the ninth electrical resistor, and the tenth electrical resistor have the same resistance value.

8. In the abnormality detection circuit according to claim 7, An abnormality detection circuit in which the resistance values ​​of the eighth electrical resistance, the ninth electrical resistance, and the tenth electrical resistance are higher than the resistance values ​​of the fifth electrical resistance, the sixth electrical resistance, and the seventh electrical resistance.

9. The abnormality detection circuit according to any one of claims 1 to 8, An inverter for driving the aforementioned three-phase motor, A determination unit that performs an abnormality determination based on the signal output from the abnormality detection circuit, Equipped with, The determination unit is a motor drive device that performs the abnormality determination with the inverter turned off.

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