Motor drive system and air conditioner

Abstract

The motor drive system (100) according to the present invention includes: an inverter (2) that drives a motor (30); a current detection unit (3) that detects a current value of a current flowing in the inverter (2), that is, a first signal, and outputs the first signal; a first low-pass filter (4) that removes a noise frequency component from the first signal and outputs a current value with the noise frequency component removed, that is, a second signal; a demagnetization current determination unit (5) that compares a demagnetization current threshold value, which is a current value at which a permanent magnet included in the motor (30) is demagnetized, and the second signal, and outputs a demagnetization protection signal when the second signal takes a value greater than the demagnetization current threshold value; and a short-circuit determination unit (7) that compares a third signal obtained by adding the first signal and the demagnetization protection signal with a short-circuit threshold value that is equal to or less than a current value of a current flowing when a short circuit occurs in the inverter (2), and outputs an abnormality signal that stops the inverter (2) when the third signal takes a value equal to or greater than the short-circuit threshold value.

Description

Technical Field

[0001] The present invention relates to a motor drive system and an air conditioner that protect a switching element included in an inverter. Background Art

[0002] As a motor drive system for suppressing power consumption, a motor drive system is known in which a motor is formed as a non-commutator motor, that is, a brushless DC (Direct Current) motor, and a motor drive unit for driving the motor is formed as an inverter. Since the commutator of the non-commutator motor does not wear, the product life is longer than that of a commutator motor. In addition, since no current flows in the rotor of the non-commutator motor, the power consumption is smaller than that of an induction motor. Therefore, the non-commutator motor can suppress power consumption and is thus widely used in products represented by air conditioners.

[0003] In order to protect a switching element included in an inverter, protect a motor connected to the inverter, and protect a power source connected to the inverter, an overcurrent detection unit for detecting an overcurrent is usually provided in the inverter.

[0004] Patent Document 1 discloses a motor drive system including a protection unit that protects a switching element when a large current flows in an inverter, and a protection unit that protects a power source from the influence of a large current.

[0005] For the purpose of protecting an inverter, it is necessary to provide a plurality of overcurrent detection units in a motor drive system. Among the overcurrents generated in the inverter, an overcurrent generated particularly due to a short circuit of a switching element constituting the inverter flows a large current in a short time. Therefore, in the case where an overcurrent is generated due to a short circuit of a switching element, the inverter should be stopped most rapidly. In addition, in the case where a plurality of overcurrent detection units are provided, it is possible to consider combining protection against the short circuit and protection against other currents.

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-81285

[0007] In the conventional protection against overcurrent, if a plurality of overcurrent detection units are provided, a plurality of output lines for abnormal signals are required. For example, in the case of transmitting an abnormal signal to a gate drive signal generation circuit of a switching element, it may not be possible to connect a plurality of abnormal signal lines. In addition, even in the case of transmitting an abnormal signal to a microcomputer that is a control unit of a motor drive system, since the number of ports of the microcomputer is limited, it is sometimes desired to limit the ports used to the minimum. Summary of the Invention

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to obtain a motor drive system capable of transmitting abnormal signals from a plurality of overcurrent detection units through one abnormal signal output line.

[0009] In order to solve the above problems and achieve the object, the motor drive system according to the present invention includes: an inverter that drives a motor; a current detection unit that detects a current value of a current flowing in the inverter, that is, a first signal, and outputs the first signal; a first low-pass filter that removes a noise frequency component from the first signal and outputs a current value obtained by removing the noise frequency component, that is, a second signal; a demagnetization current determination unit that compares a demagnetization current threshold value, which is a current value at which a permanent magnet included in the motor demagnetizes, with the second signal, and outputs a demagnetization protection signal when the second signal takes a value larger than the demagnetization current threshold value; and a short-circuit determination unit that compares a third signal obtained by adding the first signal and the demagnetization protection signal with a short-circuit threshold value that is equal to or less than a current value of a current flowing when a short circuit occurs in the inverter, and outputs an abnormal signal for stopping the inverter when the third signal takes a value equal to or higher than the short-circuit threshold value.

[0010] According to the present invention, the following effect is achieved: It is possible to obtain a motor drive system capable of transmitting abnormal signals from a plurality of overcurrent detection units through one abnormal signal output line. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 FIG. 1 shows a motor drive system according to Embodiment 1 of the present invention.

[0012] Figure 2 FIG. 2 shows a configuration example of a control circuit according to Embodiment 1 of the present invention.

[0013] Figure 3 FIG. 3 shows a relationship between a short-circuit current value of a switching element and an overcurrent value of a motor according to Embodiment 1 of the present invention.

[0014] Figure 4 FIG. 4 shows a motor drive system according to Embodiment 1 of the present invention.

[0015] Figure 5 FIG. 5 shows a motor drive system according to Embodiment 1 of the present invention.

[0016] Figure 6 FIG. 6 shows a motor drive system according to Embodiment 2 of the present invention.

[0017] Figure 7 FIG. 7 shows a relationship between a short-circuit current of an inverter, a demagnetization current of a motor, and a value of a module overcurrent according to Embodiment 2 of the present invention, and a relationship between a time when the inverter should be stopped.

[0018] Figure 8 This is a diagram showing the current value of the inverter when the current value related to Embodiment 2 of the present invention is greater than the short-circuit threshold value.

[0019] Figure 9 This is a diagram showing the current value of the inverter when the current value related to Embodiment 2 of the present invention is greater than the demagnetization current threshold value.

[0020] Figure 10 This is a diagram showing the current value of the inverter when the current value related to Embodiment 2 of the present invention is greater than the overcurrent threshold value. Detailed Embodiment

[0021] Hereinafter, the motor drive system and the air conditioner related to the embodiments of the present invention will be described in detail based on the drawings. In addition, the present invention is not limited to this embodiment.

[0022] Embodiment 1

[0023] Figure 1 This is the first diagram showing the motor drive system 100 related to Embodiment 1 of the present invention. The motor drive system 100 includes a rectifier circuit 1, an inverter 2, a current detection unit 3, a first low-pass filter 4, a demagnetization current determination unit 5, a demagnetization current threshold holding unit 6, a short-circuit determination unit 7, and a short-circuit threshold holding unit 8.

[0024] The rectifier circuit 1 has four diodes 11 to 14 connected in a bridge and a capacitor 15. The rectifier circuit 1 uses the diodes 11 to 14 and the capacitor 15 to rectify the AC voltage output from the AC power supply 60 into a DC voltage, and applies the rectified DC voltage to the inverter 2. The inverter 2 includes six switching elements 21 to 26, converts the DC voltage into an AC voltage, and applies the AC voltage to the motor 30. For each of the switching elements 21 to 26, when not distinguished, it is referred to as the switching element 20.

[0025] Although the switching elements 21 to 26 are exemplified as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) formed of a silicon-based material, the switching elements 21 to 26 are not limited to MOSFETs, and may also be MOSFETs formed of wide bandgap (WBG) semiconductors such as silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), or diamond. Generally, wide bandgap semiconductors have higher breakdown voltage and heat resistance than silicon semiconductors. Therefore, by using a wide bandgap semiconductor for at least one of the switching elements 21 to 26, the breakdown voltage resistance and allowable current density of the switching elements can be increased, and thus the semiconductor module assembled with the switching elements can be miniaturized.

[0026] The current detection unit 3 is connected to the inverter 2 and detects the current value flowing in the inverter 2. In addition, the current detection unit 3 outputs the information of the detected current value to the demagnetization current determination unit 5 via the first low-pass filter 4. In addition, the current detection unit 3 outputs the information of the current value to the short-circuit determination unit 7 via the diode 16.

[0027] The first low-pass filter 4 removes the noise frequency component from the information of the current value and outputs the information of the current value after removing the noise frequency component to the demagnetization current determination unit 5. The demagnetization current determination unit 5 uses the demagnetization current threshold value and the information of the current value, and when the information of the current value is a value larger than the demagnetization current threshold value, outputs the demagnetization protection signal to the short-circuit determination unit 7 via the diode 17. The demagnetization current threshold value holding unit 6 holds the demagnetization current threshold value. The demagnetization current threshold value refers to the current value flowing in the motor 30 when the permanent magnet of the motor 30 is demagnetized.

[0028] The short-circuit determination unit 7 uses the information of the current value and the short-circuit threshold value, and when the information of the current value is equal to or higher than the short-circuit threshold value, outputs an abnormal signal to a drive signal generation unit (not shown) or a control unit (not shown) that controls the motor drive system 100. The abnormal signal is a signal that controls the operation of the switching elements 21 to 26 of the inverter 2. By causing the short-circuit determination unit 7 to output the abnormal signal, the operation of the inverter 2 can be stopped when an abnormality occurs in the motor drive system 100. The short-circuit threshold value holding unit 8 holds the short-circuit threshold value. The short-circuit threshold value refers to a value equal to or lower than the current value of the current flowing in the inverter 2 during a short circuit.

[0029] The hardware configurations of the current detection unit 3, the demagnetization current determination unit 5, the demagnetization current threshold value holding unit 6, the short-circuit determination unit 7, and the short-circuit threshold value holding unit 8 according to the embodiment of the present invention will be described. The demagnetization current determination unit 5 and the short-circuit determination unit 7 are implemented by resistors, capacitors, diodes, comparators, or combinations thereof. The short-circuit threshold value holding unit 8 and the demagnetization current threshold value holding unit 6 are implemented by an electronic circuit that performs each process, that is, a processing circuit.

[0030] The processing circuit according to the embodiment of the present invention may be dedicated hardware or a control circuit including a memory and a CPU (Central Processing Unit) that executes a program stored in the memory. Here, the memory is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), or a flash memory. Figure 2FIG. 0 is a diagram showing a configuration example of a control circuit 500 according to Embodiment 1 of the present invention. In the case where the processing circuit is dedicated hardware, the processing circuit is, for example, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0031] As Figure 2 shown, the control circuit 500 includes a processor 500a serving as a CPU and a memory 500b. When the demagnetization current determination unit 5, the demagnetization current threshold holding unit 6, the short-circuit determination unit 7, and the short-circuit threshold holding unit 8 are implemented by the control circuit 500 shown Figure 2 herein, they are implemented by the processor 500a reading and executing programs corresponding to the respective processes stored in the memory 500b. In addition, the memory 500b also serves as a temporary memory in each process implemented by the processor 500a. Further, the demagnetization current determination unit 5 and the short-circuit determination unit 7 may also be implemented by the control circuit 500. The current detection unit 3 is, for example, a current sensor.

[0032] The operation of the short-circuit determination will be described. When a short circuit occurs in any one of the switching elements 21 to 26, for example, when the switching elements 21 and 22 are both turned on due to malfunction, the DC voltage applied by the rectifier circuit 1 is short-circuited. Therefore, the current flowing in the inverter 2 increases rapidly. There are two paths for transmitting the information of the current value to the short-circuit determination unit 7, that is, a path via the first low-pass filter 4 and a path via the anti-backflow diode 16. In the path via the first low-pass filter 4, a delay is caused by the first low-pass filter 4. Therefore, the short-circuit determination unit 7 performs short-circuit determination based on the information of the current received from the path via the diode 16 where no delay occurs.

[0033] The short-circuit determination unit 7 compares the information of the current value with the short-circuit threshold. When the information of the current value is equal to or greater than the short-circuit threshold, an abnormal signal is output to the drive signal generation unit or the control unit, thereby setting all of the switching elements 21 to 26 of the inverter 2 to the off state and urgently stopping the operation of the inverter 2. Here, the short-circuit threshold is set to a value within the range where the switching element is ensured not to malfunction, that is, within the so-called short-circuit SOA (Safe Operating Area). By this operation, it is possible to prevent the switching element 20 from being damaged when an unexpected short circuit occurs.

[0034] Next, the operation of the demagnetization current determination unit 5 will be described. Since the motor 30 has inductance, the rate of increase of the current flowing in the motor 30 is slower than the rate of increase of the current flowing during the short circuit of the switching elements 21 to 26. Therefore, by passing the information of the current value output by the current detection unit 3 through the first low-pass filter 4, false detection caused by noise in the information of the current value is suppressed.

[0035] Figure 3 is a diagram showing the relationship between the short-circuit current value of the switching element 20 and the overcurrent value of the motor 30 according to Embodiment 1 of the present invention. In Figure 3 the vertical axis represents the current value and the horizontal axis represents time. As Figure 3 shown, it can be seen that the inverter short-circuit current generated due to the short circuit of the switching element 20 increases at a faster rate than the motor overcurrent flowing in the motor 30. In addition, it can be seen that the short-circuit threshold is greater than the demagnetization current threshold.

[0036] When the information of the current value that has passed through the first low-pass filter 4 is greater than the demagnetization current threshold, the demagnetization current determination unit 5 outputs a demagnetization protection signal to the short-circuit determination unit 7 via the diode 17. Here, the demagnetization protection signal is output as a value greater than the short-circuit threshold and is input to the short-circuit determination unit 7. Therefore, the short-circuit determination unit 7 outputs an abnormal signal, sets all the switching elements 21 to 26 included in the inverter 2 to the off state, and urgently stops the operation of the inverter 2. Among them, the demagnetization current threshold is set to be equal to or lower than the demagnetization current value of the motor 30. By this operation, the permanent magnet included in the motor 30 can be protected from unexpected demagnetization.

[0037] Figure 4 is a second diagram showing the motor drive system 100a according to Embodiment 1 of the present invention. In the motor drive system 100a, the demagnetization current determination unit 5, the demagnetization current threshold holding unit 6, the short-circuit determination unit 7, and the short-circuit threshold holding unit 8 are provided in the inverter module 40, and the inverter module 40 includes the inverter 2. In addition, instead of outputting a demagnetization protection signal to the short-circuit determination unit 7, the demagnetization current determination unit 5 outputs an abnormal signal to the drive signal generation unit 41. Figure 5 is a third diagram showing the motor drive system 100b according to Embodiment 1 of the present invention. In the motor drive system 100b, the short-circuit determination unit 7 and the short-circuit threshold holding unit 8 are provided in the inverter module 40. Thus, in Embodiment 1, as Figure 4 、 Figure 5 shown, the short-circuit determination unit 7, the demagnetization current determination unit 5, or both of them can be provided in the inverter module 40. In addition, in Figure 4 and Figure 5In this case, the short-circuit determination unit 7 is configured to output an abnormal signal to the drive signal generation unit 41. The drive signal generation unit 41 generates a drive signal under the control of the control unit 42.

[0038] As described above, in the first embodiment of the present invention, the motor drive system 100 includes: an inverter 2 that drives a motor 30; a current detection unit 3 that detects the current value of the current flowing in the inverter 2, that is, the first signal, and outputs the first signal; a first low-pass filter 4 that removes the noise frequency component from the first signal and outputs the current value with the noise frequency component removed, that is, the second signal; a demagnetization current determination unit 5 that compares the demagnetization current threshold value, which is the current value at which the permanent magnet of the motor 30 is demagnetized, and the second signal, and outputs a demagnetization protection signal when the second signal takes a value greater than the demagnetization current threshold value; and a short-circuit determination unit 7 that compares the third signal obtained by adding the first signal and the demagnetization protection signal with a short-circuit threshold value that is equal to or less than the current value of the current flowing when a short circuit occurs in the inverter. When the third signal takes a value equal to or greater than the short-circuit threshold value, the short-circuit determination unit 7 outputs an abnormal signal to stop the inverter 2. Therefore, the motor drive system 100 can protect the switching element 20 when a short circuit occurs and protect the motor 30 from demagnetization by outputting one abnormal signal.

[0039] Embodiment 2

[0040] In the first embodiment, although the motor drive system 100 is protected from short-circuit current and demagnetization current, in the second embodiment, on top of that, the motor drive system 100c also protects the inverter module including the inverter 2 from overcurrent. Among them, the constituent elements having the same functions as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the repeated descriptions are omitted.

[0041] Figure 6 FIG. is a diagram showing a motor drive system 100c according to the second embodiment of the present invention. The motor drive system 100c further includes a second low-pass filter 31, a module overcurrent determination unit 32, and a module overcurrent threshold holding unit 33 on the basis of the configuration of the first embodiment. The module overcurrent determination unit 32 uses the information of the current value and the module overcurrent threshold value, and determines that an overcurrent is flowing in the inverter module when the information of the current value is greater than the module overcurrent threshold value, and outputs an overcurrent signal to the short-circuit determination unit 7 via a diode 18. The module overcurrent threshold value is the current value used to determine that an overcurrent is flowing in the inverter module 40. The module overcurrent threshold holding unit 33 holds the module overcurrent threshold value. The second low-pass filter 31 is connected to the front stage of the module overcurrent determination unit 32. In addition, the time constant of the second low-pass filter 31 is greater than the time constant of the first low-pass filter 4.

[0042] The operation of the module overcurrent determination unit 32 will be described. In an inverter module, an upper limit value of the current that can ensure operation, that is, a rated current value, is defined. Basically, a current equal to or less than the rated current value needs to flow through the inverter module. However, even if the rated current value is instantaneously exceeded, the inverter module can withstand it. Therefore, the rated current value of the inverter module is less than the demagnetizing current value. Although a period during which the current exceeds the rated current of the module occurs when the current rapidly rises to reach the demagnetizing current value, if this period is short, the inverter module can withstand it. However, when the period during which the current exceeds the rated current of the module is longer than a predetermined period, it is necessary to stop the power supply to the inverter 2.

[0043] Figure 7 FIG. is a diagram showing the relationship between the short-circuit current of the inverter 2, the overcurrent value of the motor 30, and the module overcurrent value according to Embodiment 2 of the present invention, and the relationship between the time when the inverter 2 should be stopped. As Figure 7 shown, it can be seen that the module overcurrent increases more slowly than the current value of the motor overcurrent. In addition, it can be seen that the overcurrent threshold is less than the demagnetizing current threshold.

[0044] Figure 8 FIG. is a diagram showing the current value of the inverter 2 when the current value according to Embodiment 2 of the present invention is greater than the short-circuit threshold. Figure 9 FIG. is a diagram showing the current value of the inverter 2 when the current value according to Embodiment 2 of the present invention is greater than the demagnetizing current threshold. Figure 10 FIG. is a diagram showing the current value of the inverter 2 when the current value according to Embodiment 2 of the present invention is greater than the overcurrent threshold. Figures 8 - 10 The vertical axis represents the current value and the horizontal axis represents the time, respectively. As Figure 8 shown, in the case of a short circuit, the current value of the inverter 2 rapidly increases and becomes the same as the short-circuit threshold value at an early stage. As Figure 9 shown, when the current value exceeds the demagnetizing current threshold, the current value of the inverter 2 increases more slowly than in the case of a short circuit and exceeds the demagnetizing current threshold. As Figure 10 shown, when the current value exceeds the overcurrent threshold, the current value of the inverter 2 increases slowly and exceeds the overcurrent threshold.

[0045] The second low-pass filter 31 will be described. The time constant of the second low-pass filter 31 is longer than the time constant of the first low-pass filter 4. Thus, the module overcurrent determination unit 32 does not output an abnormal signal when the current flowing through the inverter 2 exceeds the module overcurrent threshold in a short time, but the short-circuit determination unit 7 outputs an abnormal signal when the time during which the current exceeds the module overcurrent threshold becomes long.

[0046] Since the overcurrent signal output by the module overcurrent determination unit 32 is greater than the threshold value of the short-circuit determination unit 7, if an overcurrent signal is input, the short-circuit determination unit 7 outputs an abnormal signal, sets all the switching elements 20 of the inverter 2 to the off state, and emergency stops the operation. In addition to short-circuit protection and demagnetization protection, it is also possible to protect the module from the influence of overcurrent.

[0047] As described above, the motor drive system 100c according to the second embodiment of the present invention further includes, on the basis of the configuration of the motor drive system 100: a second low-pass filter 31 that removes the noise frequency component from the first signal and outputs a current value with the noise frequency component removed, that is, the fourth signal, and has a time constant longer than that of the first low-pass filter 4; a module overcurrent determination unit 32 that compares the fourth signal with an upper limit value of the current that can ensure the operation of the inverter module 40 including the inverter 2, that is, the module overcurrent threshold, and outputs an overcurrent signal when the fourth signal takes a value larger than the module overcurrent threshold, and the short-circuit determination unit 7 uses the overcurrent signal to output an abnormal signal for stopping the inverter 2.

[0048] In addition, in the first and second embodiments, the module overcurrent determination unit 32, the demagnetization current determination unit 5, and the short-circuit determination unit 7 may also be configured as circuits on an electronic substrate. Alternatively, the module overcurrent determination unit 32, the demagnetization current determination unit 5, and the short-circuit determination unit 7, or at least one of these determination units may be configured within a microcomputer serving as the control unit 42 or within the inverter module 40. By configuring the module overcurrent determination unit 32, the demagnetization current determination unit 5, and the short-circuit determination unit 7, or at least one of these determination units within the inverter module 40, the circuit area can be eliminated. In addition, by configuring the module overcurrent determination unit 32, the demagnetization current determination unit 5, and the short-circuit determination unit 7, or at least one of these determination units within the inverter module 40, the influence of noise from the outside of the inverter module 40 can be suppressed, thereby improving the noise resistance.

[0049] In the first and second embodiments, the motor 30 connected to the inverter 2 may also be a motor that drives a compressor or a fan of an air conditioner.

[0050] The configurations shown in the above embodiments are examples showing the content of the present invention, and may be combined with other known technologies, or a part of the configuration may be omitted or changed without departing from the gist of the present invention.

[0051] Description of reference numerals

[0052] 1...Rectifier circuit; 2...Inverter; 3...Current detection unit; 4...First low-pass filter; 5...Demagnetizing current determination unit; 6...Demagnetizing current threshold holding unit; 7...Short-circuit determination unit; 8...Short-circuit threshold holding unit; 11 to 14, 16 to 18...Diodes; 15...Capacitor; 20 to 26...Switching elements; 30...Motor; 31...Second low-pass filter; 32...Module overcurrent determination unit; 33...Module overcurrent threshold holding unit; 40...Inverter module; 41...Drive signal generation unit; 42...Control unit; 60...AC power supply; 100, 100a, 100b, 100c...Motor drive system; 500...Control circuit; 500a...Processor; 500b...Memory.

Claims

1. A motor drive system, characterized in that: It includes: An inverter that drives a motor; A current detection unit that detects the current value of the current flowing in the inverter, that is, the first signal, and outputs the first signal; A first low-pass filter that removes the noise frequency component from the first signal and outputs the current value with the noise frequency component removed, that is, the second signal; A demagnetization current determination unit that compares the current value at which the permanent magnet of the motor demagnetizes, that is, the demagnetization current threshold, and the second signal. When the second signal takes a value greater than the demagnetization current threshold, it outputs a demagnetization protection signal greater than the short-circuit threshold for detecting a short circuit in the inverter, that is, greater than the demagnetization current threshold; And A short-circuit determination unit that compares the third signal obtained by adding the first signal and the demagnetization protection signal with the short-circuit threshold. When the third signal takes a value equal to or greater than the short-circuit threshold, it outputs an abnormal signal that stops the inverter.

2. The motor drive system according to claim 1, characterized in that: The motor drive system further includes a first diode that inputs the demagnetization protection signal to the anode and a second diode that inputs the first signal to the anode. The third signal is a signal obtained by adding the output of the cathode of the first diode and the output of the cathode of the second diode.

3. The motor drive system according to claim 2, characterized in that: The motor drive system includes: A second low-pass filter that removes the noise frequency component from the first signal and outputs the current value with the noise frequency component removed, that is, the fourth signal, and has a longer time constant than the first low-pass filter; And A module overcurrent determination unit that compares the fourth signal with the upper limit value of the current that can ensure the operation of the inverter module having the inverter, that is, the module overcurrent threshold smaller than the demagnetization current threshold. When the fourth signal takes a value greater than the module overcurrent threshold, it outputs an overcurrent signal greater than the short-circuit threshold, The short-circuit determination unit uses the overcurrent signal to output the abnormal signal that stops the inverter.

4. The motor drive system according to any one of claims 1 to 3, characterized in that: The motor drive system includes a drive signal generation unit that generates drive signals for controlling a plurality of switching elements included in the inverter, If the drive signal generation unit is input with the abnormal signal, it stops the operation of the inverter.

5. The motor drive system according to claim 4, characterized in that: The motor drive system includes a control unit that controls the drive signal generation unit, If the control unit is input with the abnormal signal, it stops the operation of the inverter.

6. The motor drive system according to any one of claims 1 to 3, characterized in that: The demagnetization current determination unit is provided in the inverter module of the inverter.

7. The motor drive system according to any one of claims 1 to 3, characterized in that: The short-circuit determination unit is provided in the inverter module of the inverter.

8. The motor drive system according to any one of claims 1 to 3, characterized in that the plurality of switching elements included in the inverter are wide bandgap semiconductors.

9. An air conditioner, characterized in that it includes the motor drive system according to any one of claims 1 to 8.

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