JP2012175871A - Motor controller and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller capable of performing consumption processing on regenerative electric power using a small-scale, low-capacity regenerative resistor.SOLUTION: The motor controller includes: a converter circuit which generates a bus voltage; an inverter circuit which converts the bus voltage applied across itself into an AC voltage of arbitrary level and frequency and supplies the AC voltage to a motor; a regenerative circuit including a series circuit of the regenerative resistor connected in parallel to the inverter circuit and applied with the bus voltage across itself and a regenerative transistor; and control means of turning on the regenerative transistor so that when the bus voltage exceeds a predetermined value owing to the regenerative electric power from the motor, the regenerative resistor is made to consume the regenerative electric power. The control means performs variable control over an ON time rate of the regenerative transistor according to a regenerative load rate as a state of the regenerative circuit.

Description

  The present invention relates to a motor control device that drives and controls a motor by an inverter system, and a motor control system in which a plurality of motor control devices are connected so that their buses are common buses.

  When the motor is decelerated from high speed operation, the motor operates as a generator. For this reason, in motor control devices that drive and control motors using an inverter system, regenerative power from the motor is consumed between the positive and negative buses in order to suppress an increase in bus voltage due to regenerative power from the motor. A regenerative circuit for processing is provided. This regenerative circuit includes a series circuit of a regenerative transistor and a regenerative resistor in which a bus voltage is applied to both ends. Further, as the operating voltage of the regenerative circuit, a bus voltage that determines that the regenerative transistor is turned on (referred to as a regenerative transistor on voltage) and a bus voltage that determines that the regenerative transistor is turned off (the regenerative transistor off voltage and Defined).

  Here, in the conventional regenerative power consumption processing method performed in the motor control device, when the bus voltage becomes the ON voltage of the regenerative transistor, the regenerative transistor is continuously operated until the bus voltage becomes equal to or lower than the OFF voltage of the regenerative transistor. To turn it on.

  In addition, a process for consuming regenerative power from a motor is necessary in a motor control system in which a plurality of motor control devices are connected so that each bus is a common bus, and various proposals have been made (for example, Patent documents 1 to 3).

  The regenerative power consumption processing method described in Patent Document 1 includes a system controller for controlling a motor control system, and the system controller uses a regenerative load based on regenerative load information transferred from each motor control device. The operation level of the regenerative circuit of each motor control device is made equal by raising the operation level of the regenerative circuit of the motor control device having a large regenerative power and lowering the operation level of the regenerative circuit of the motor control device having a small regenerative load.

  The regenerative power consumption processing method described in Patent Document 2 is a state of a drive signal of a regenerative transistor that indicates an on / off state of the regenerative transistor between a plurality of motor control devices in which the buses are connected in parallel. If any one of the ON signals is present, the regeneration transistors of all the plurality of motor control devices connected in parallel are turned on to equalize the load on the regeneration circuit.

  The regenerative power consumption processing method described in Patent Document 3 is a method in which the ON voltage of the regenerative transistor constituting the regenerative circuit of the motor control device is made variable independently in each motor control device in accordance with the state of the regenerative circuit. Thus, signal transmission between the controller and other motor control devices is not required, the circuit configuration can be simplified, and power consumption due to the regenerative resistance of each motor control device is equalized.

JP 11-89285 A JP-A-2005-253213 JP 2010-110139 A

  However, in the regenerative power consumption processing method in the conventional motor control device, since the regenerative current flows continuously through the regenerative resistor, it is difficult to reduce the size and reduce the capacity of the regenerative resistor, which reduces the cost. Have difficulty.

  In addition, the prior arts described in Patent Document 1 and Patent Document 2 are either between the system controller and the motor control device or between each motor control device in order to equalize the regenerative load of each motor control device. There is a problem that information exchange between them is necessary, and a circuit configuration of a signal transmission system or the like becomes complicated. The prior art described in Patent Document 3 enables simplification of these circuit configurations and realizes equalization of the regenerative load by making the ON voltage of the regenerative transistor of each motor control device variable independently. is doing.

  However, in the method described in Patent Document 3, in a system configuration in which a plurality of motor control devices are connected by a common bus, for example, the load of one regenerative circuit among the regenerative circuits of the plurality of motor control devices is 100%. In such a case, the protection function may be activated while remaining power is provided to the regenerative circuit of the other motor control device.

  For example, in a motor control device (assumed to be A) that detects the bus voltage highest due to component variations, when the regenerative power returns from the motor, the regenerative processing is performed first, and the regenerative load factor increases. Then, processing for increasing the on-voltage level of the regenerative transistor is performed. Further, since the motor control device that is not performing the regenerative operation other than the motor control device A has a low regenerative load factor, the on-voltage level of the regenerative transistor is low, and regenerative processing is easily performed.

  However, in this case, the regenerative power returned from the motor is below the maximum value that can be set as the ON voltage level of the regenerative transistor of the motor control device A even if the regenerative transistors of all the regenerative circuits in the system are turned on. When the electric power is such that the voltage does not decrease, regeneration processing is simultaneously performed in the motor control device A and all the remaining motor control devices. However, the regenerative load factor of the motor control device A is at the protection level and the protection function is activated even though the regenerative load factor of all the motor control devices including the motor control device A is still in the state of remaining power. May end up.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a motor control device capable of performing regenerative power consumption processing using a small-scale and low-capacity regenerative resistor.

  Another object of the present invention is to provide a motor control system that can perform a process for consuming regenerative power by using the capacity of all regenerative circuits to the maximum using the motor control device according to the present invention.

  In order to solve the above-described problems and achieve the object, a motor control device according to the present invention includes a converter circuit that generates a bus voltage, and the bus voltage applied to both ends of the AC voltage having an arbitrary magnitude and frequency. An inverter circuit that is converted into a motor and supplied to the motor, a regenerative circuit that is connected in parallel to the inverter circuit and that has a regenerative resistor and a regenerative transistor connected to the bus voltage at both ends, and a regenerative circuit from the motor When the bus voltage exceeds a predetermined value due to electric power, the motor control device includes a control unit that turns on the regenerative transistor so that the regenerative power is consumed by the regenerative resistor. The on-time ratio of the regenerative transistor is variably controlled in accordance with the regenerative load factor which is the state of the regenerative circuit.

  According to the present invention, since the regenerative current flows intermittently instead of continuously flowing in the regenerative resistor, the regenerative power consumption processing can be performed using a small-scale and low-capacity regenerative resistor. it can. Therefore, there is an effect that the cost of the motor control device can be reduced.

FIG. 1 is a block diagram showing a configuration of a motor control device according to Embodiment 1 of the present invention. FIG. 2 is a time chart for explaining the regenerative power consumption processing operation. FIG. 3 is a block diagram showing the configuration of the motor control system according to the second embodiment of the present invention. FIG. 4 is a characteristic diagram for explaining another example of a method for variably controlling the on-time ratio of the regenerative transistor according to the regenerative load factor which is the state of the regenerative circuit, as the third embodiment of the present invention.

  Embodiments of a motor control device and system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a motor control device according to Embodiment 1 of the present invention. In FIG. 1, a three-phase AC power source 1 is connected to AC input terminals L1, L2, and L3 of a motor control device 2, and a motor 10 is connected to output terminals U, V, and W as a load.

  The motor control device 2 includes a converter circuit 3, a regenerative circuit 6, a voltage type inverter circuit 9, a bus voltage detection circuit 11, a regenerative transistor drive circuit 12, an inverter drive circuit 13, and a calculation unit 14. Yes.

  The converter circuit 3 includes a diode stack 4 and a main circuit capacitor 5. The diode stack 4 converts the three-phase AC voltage fed from the AC input terminals L1, L2, and L3 into a DC voltage. A positive electrode bus P is connected to the positive electrode output terminal of the diode stack 4, and a negative electrode bus N is connected to the negative electrode output terminal of the diode stack 4. The main circuit capacitor 5 is connected between the positive electrode bus P and the negative electrode bus N, smoothes the output voltage of the diode stack 4, and forms a predetermined bus voltage between the positive electrode bus P and the negative electrode bus N.

  In the voltage type inverter circuit 9, three sets of upper and lower arm switching elements are connected in parallel between the positive bus P and the negative bus N, and each switching element switches the bus voltage by a drive signal from the inverter drive circuit 13. Thus, the bus voltage is converted into an AC voltage having an arbitrary magnitude and frequency, and a drive signal is output from the output terminals U, V, W to the motor 10.

  The motor 10 performs a power running operation and a regenerative operation. When the motor 10 performs a regenerative operation, the regenerative electric power charges the main circuit capacitor 5 via the voltage type inverter circuit 9 to raise and change the bus voltage.

  The regenerative circuit 6 includes a regenerative transistor 7 and a regenerative resistor 8 connected in series between the positive electrode bus P and the negative electrode bus N. In the first embodiment, the regenerative transistor 7 is turned on / off by a drive signal that changes the on-time width supplied from the regenerative transistor drive circuit 12 when the bus voltage changes by a predetermined amount due to the regenerative power from the motor 10. Driven off. As a result, the regenerative power from the motor 10 is consumed by the regenerative resistor 8.

  The bus voltage detection circuit 11 detects the bus voltage and outputs it to the calculation unit 14. The regenerative transistor drive circuit 12 generates a drive signal whose on-time width varies according to the drive command signal according to the first embodiment from the arithmetic unit 14 and drives the regenerative transistor 7 on and off. The inverter drive circuit 13 causes each switching element of the voltage type inverter circuit 9 to perform a switching operation according to the PWM voltage command from the calculation unit 14.

  The calculation unit 14 performs a process of calculating a PWM voltage command from feedback information such as the detected rotation speed and current value of the motor 10 and applying the PWM voltage command to the inverter drive circuit 13 as control means for controlling the operation of the motor 10.

  In addition, the calculation unit 14 is a control unit that performs a process of consuming regenerative power, and an on-voltage and an off-voltage of the regenerative transistor 7 that are operating voltages of the regenerative circuit 6 with respect to the bus voltage are determined in advance. 11 is compared with a predetermined operating voltage of the regenerative circuit 6, and when the bus voltage exceeds the ON voltage of the regenerative transistor 7, the regenerative transistor 7 is turned on to generate regenerative power. Processing to be consumed by the device 8 (processing to lower the bus voltage to the off voltage of the regenerative transistor 7 or less) is performed.

  In general, the regenerative power consumption processing method is such that the regenerative transistor 7 is continuously turned on until the bus voltage drops below the off voltage of the regenerative transistor 7 so that the bus voltage is turned off. This is a method of turning off when the voltage drops below the voltage.

  On the other hand, in the regenerative power consumption processing method according to the first embodiment, the conduction time (on-time ratio) of the regenerative transistor 7 is set in the regenerative circuit 6 until the bus voltage drops below the off voltage of the regenerative transistor 7. This is a method of varying according to the regenerative load factor which is the state. The calculation unit 14 according to the first embodiment generates a drive command signal having such contents and supplies it to the regenerative transistor drive circuit 12.

  Here, the regenerative load factor is calculated based on, for example, a preset ON voltage of the regenerative transistor 7 and an ON time width of the regenerative transistor 7. The on-time ratio of the regenerative transistor 7 is determined with the unit time width that defines the regenerative processing operation being 100%.

  Hereinafter, the regenerative power consumption processing operation according to this embodiment will be described in detail with reference to FIG. FIG. 2 is a time chart for explaining the regenerative power consumption processing operation. In FIG. 2, (1) the operating voltage of the regenerative circuit with respect to the bus voltage, (2) the regenerative load factor that is the state of the regenerative circuit, and (3) the on (ON) / off (OFF) state of the regenerative transistor are: It is shown. Times t <b> 0 to t <b> 7 shown at equal intervals are times for determining the start / end of the unit time that defines the processing operation that consumes the regenerative power and the on-time ratio of the regenerative transistor 7. In this example, time t0 is the start time of the regenerative power processing operation, and time t6 is the time of recognizing the end of the regenerative power processing operation.

  In FIG. 2A, the bus voltage 21 before the regenerative power processing operation start time t0 is a bus voltage when the motor 10 does not return from the regenerative power to the bus. Bus voltage 22 at times t0 to t7 is a bus voltage generated by regenerative power returned from motor 10 to the bus. The bus voltage 22 is shown in a pattern that rises rapidly from the bus voltage 21 immediately before time t0, and drops after the time t0 due to the consumption processing according to the first embodiment.

  As shown in FIG. 2 (1), as the operating voltage of the regenerative circuit 6, the off voltage 23 of the regenerative transistor 7 is set to a predetermined voltage higher than the bus voltage 21. The ON voltage 24 of the regenerative transistor 7 is a predetermined voltage higher than the OFF voltage 23, and is determined in consideration of the regenerative power processing capability of the regenerative circuit 6, the magnitude of the regenerative power returned from the motor 10, and the like.

  In FIG. 2 (2), the magnitude (%) of the regenerative load factor used for the regenerative power consumption process is such that the first judgment load factor 26 <the second judgment load factor 28 <the third judgment load factor 30. An example is shown in which three determination load factors 26, 28, and 30 that are related are used.

  2 (1), (2), and (3), until the regenerative power processing operation start time t0, the regenerative transistor 7 is off and the regenerative load factor 25 is 0%. In this state, when the regenerative power is returned from the motor 10 and it is detected that the bus voltage 21 has increased to the bus voltage 22 exceeding the ON voltage 24 of the regenerative transistor 7, the regenerative transistor 7 is turned on at time t0. The regenerative power consumption processing operation is started. The regenerative load factor 25 rises due to the thermal time constant of the regenerative resistor 8 and the value of the flowing current. Note that the first determination load factor 26 is 60%, for example. When the judgment load factor 26 is reached, the ON time ratio per unit time is controlled to be 80%, for example. As shown in FIG. 2 (3), the control method at this time may be continuously ON and may be 80%, or may be further subdivided as in a PWM signal and the ON time ratio per unit time is 80% in total. There is also. Further, the on-time ratio is determined at the timing of times t0 to t7 as described above. The bus voltage 22 while the regenerative transistor 7 is on decreases from the on voltage 24 toward the off voltage 23.

  In FIG. 2 (2), the regenerative load factor 25 at the calculation timings at times t 0, t 1, t 2 does not exceed the first determination load factor 26. Therefore, as shown in FIG. 2 (3), the on-time ratio of the regenerative transistor 7 is 100% in each unit time between time t0 and t1, between time t1 and t2, and between time t2 and t3. Next, since the first determination load factor 26 is exceeded at time t3 for determining the on-time ratio of the regenerative transistor 7, the on-time ratio of the regenerative transistor 7 calculated at time t3 is 80%.

  Within the unit time between times t3 and t4, for example, the bus voltage 22 continues to be affected by the regenerative power. Therefore, when the regenerative transistor 7 is turned off, the bus voltage 22 starts to rise. On the other hand, the regenerative load factor 25 decreases and decreases to the load factor 27 at time t4.

  At time t4 that defines the processing operation, the bus voltage 22 has not yet become the off voltage 23 or less, and the load factor 27 exceeds a predetermined second determination load factor 28 (for example, 70%). The on-time ratio of the regeneration transistor 7 between t4 and t5 is determined to be 70%, for example, and the regeneration process is performed. As a result, the bus voltage 22 starts to fall within the unit time between the next times t4 and t5. On the other hand, the regenerative load factor 25 increases from the load factor 27.

  Since the bus voltage 22 is still affected by the regenerative power within the unit time between the times t4 and t5, when the regenerative transistor 7 is turned off, the bus voltage 22 starts to rise. On the other hand, the regenerative load factor 25 decreases and decreases to the load factor 29 at time t5.

  At time t5 that defines the processing operation, the bus voltage 22 has not yet become the off voltage 23 or less, and the load factor 29 exceeds a predetermined third determination load factor 30 (for example, 80%). Therefore, the on-time ratio of the regenerative transistor 7 between the times t5 and t6 is determined to be 50%, for example, and the regenerative process is performed. As a result, the bus voltage 22 starts to fall within the unit time between the next times t5 and t6. In the illustrated example, the bus voltage 22 drops below the off voltage 23.

  Since the bus voltage 22 is equal to or lower than the off voltage 23 at the timing of time t6 that defines the processing operation, it is determined that the regenerative power consumption process has ended, and the regenerative transistor 7 is not turned on and the off state is continued. The regenerative load factor 25 decreases.

  As described above, in the first embodiment, when the bus voltage exceeds the ON voltage of the regenerative transistor 7, the ON time ratio of the regenerative transistor 7 is increased when the regenerative load factor is small, and the regenerative load factor is large. A plurality of determination load factors are prepared so that control can be made smaller, selected according to the detected bus voltage, and the on-time ratio of the regenerative transistor 7 is varied according to the size between the determination load factors Then, processing for consumption of regenerative power is performed.

  Note that the method of variably controlling the on-time ratio of the regenerative transistor according to the regenerative load factor that is the state of the regenerative circuit is not limited to the method shown in FIG. For example, the method shown in FIG.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing the configuration of the motor control system according to the second embodiment of the present invention. In FIG. 3, as an example of a motor control system in which a plurality of motor control devices are connected so that each bus is a common bus, two motor control devices 54 and 55 are connected to each other with a positive bus P and a negative bus N. A configuration example in which they are connected to each other is shown.

  In FIG. 3, the operation power supply of the motor control device 54 is a three-phase AC power supply 41 connected to AC input terminals L1, L2, and L3. A motor 52 is connected to the output terminals U, V, and W of the motor control device 54 as a load. The motor control device 54 includes a converter circuit 42, a regeneration circuit 44, a voltage type inverter circuit 47, a bus voltage detection circuit 48, a regeneration transistor drive circuit 49, an inverter drive circuit 50, and a calculation unit 51. Yes. Each component has the same reference numeral, but performs the same function as the same name element of the motor control device 2 shown in FIG.

  The operating power supply of the motor control device 55 is not the three-phase AC power supply 41 but a bus voltage of a common bus in which the positive bus P and the negative bus N are connected to each other. A motor 66 is connected to the output terminals U, V, and W of the motor control device 55 as a load. The motor control device 55 includes a converter circuit 56, a regenerative circuit 60, a voltage type inverter circuit 65, a bus voltage detection circuit 61, a regenerative transistor drive circuit 62, an inverter drive circuit 63, and a calculation unit 64. Yes. Each component has the same reference numeral, but performs the same function as the same name element of the motor control device 2 shown in FIG.

  However, in the configuration shown in FIG. 3, the diode stack 67 in the converter circuit 56 of the motor control device 55 can be omitted. When there are three or more units, the added motor control device has a configuration in which the bus voltage in the previous stage is used as the operation power supply.

  In the system shown in FIG. 3, the calculation unit 51 of the motor control device 54 and the calculation unit 64 of the motor control device 55 depend on the respective regenerative load ratios for the on-time ratios of the regenerative transistors 46 and 58 independently of each other. Thus, the regenerative power consumption processing is performed independently of each other. Specifically, the on-time ratio of the regenerative transistors 46 and 58 is variably controlled in accordance with the respective regenerative load factors by the method described in FIG. 2 and the method shown in FIG. Process.

  According to the second embodiment, the load is distributed to all the regenerative circuits constituting the system, the load concentration on the specific regenerative circuit is prevented, and the regenerative overload state can be avoided. The ability of the circuit can be used to the maximum. Therefore, unlike the prior art, it is not necessary to exchange signals between the host controller and the motor control device or between the motor control devices, and a bus common system can be realized with a simple circuit configuration.

  Conventionally, when a common bus system is configured using a motor controller that has a regenerative circuit with a different regenerative processing capacity value or regenerative resistance value, the regenerative circuit with a low regenerative processing capacity or low allowable regenerative power consumption is overloaded. As a result, the protection function operates and the entire system stops. Conventionally, this problem has been solved by disabling the regenerative circuit of all motor control devices or the regenerative circuit of some motor control devices with low regenerative processing capability and attaching a separate regenerative circuit. It was.

  According to the second embodiment with respect to this problem, the on-time ratio of the regenerative transistor of the motor control device having a low regenerative processing capability is shortened to prevent an increase in the regenerative load factor, and thus the protection function does not operate. Since the remaining regenerative power is processed by the regenerative circuit of the motor control device, no special adjustment or additional device is required.

  Furthermore, in an application to which the common bus system is applied, for example, an industrial device, each motor control device corresponding to each motor of a plurality of axes is driven independently, and all the motors start moving simultaneously and stop simultaneously (regeneration) The operation pattern (which returns electric power) is rare, and an operation pattern in which the operation timings of all axes are different is common.

  In such an application, the effective value of the regenerative power generated from the contents of the operation pattern can be easily calculated. If this effective power value is less than or equal to the sum of the regenerative processing capacities of a plurality of motor control devices constituting the common bus system, it is unnecessary in advance so that the effective regenerative power can be consumed. It is possible to remove the regenerative circuit or use a regenerative resistor with a low regenerative capability, which can bring about a cost reduction effect.

Embodiment 3 FIG.
FIG. 4 is a characteristic diagram for explaining another example of a method for variably controlling the on-time ratio of the regenerative transistor according to the regenerative load factor which is the state of the regenerative circuit, as the third embodiment of the present invention. In FIG. 3, the vertical axis represents the on-time ratio of the regenerative transistor, and the horizontal axis represents the regenerative load ratio.

  On the vertical axis, the on-time ratio 100% and the protective on-time ratio DR are shown. The on-time ratio 100% is a time ratio equal to the unit time width of the regenerative processing operation. The protection on-time ratio DR is a predetermined time ratio during which the protection function does not operate as excessive regeneration within the unit time of the regeneration processing operation. The on-time ratio DR for protection is calculated by applying a preset power consumption value, an on-voltage of the regenerative transistor, and a known value of the regenerative resistor to Equation (1).

DR = consumable power value ÷ {(ON voltage of regenerative transistor) ² / regenerative resistance value}}
... (1)

  On the horizontal axis, the first load factor LIP and the second load factor LCP are shown. The first load factor LIP is a predetermined load factor within an allowable value of regenerative power that can be consumed by the regenerative resistor. The second load factor LCP is a limit load factor that can maintain the on-time ratio of the regenerative transistor at 100%.

  In FIG. 4, the calculation unit of the motor control device continues to set the on-time ratio of the regenerative transistor to a time ratio of 100% equal to the width of the unit time until the regenerative load ratio becomes the second load ratio LCP. From the second load factor LCP to the first load factor LIP, the regenerative load factor is decreased functionally from the time ratio of 100% toward the protection on-time width DR, and the regenerative load factor is the first load factor LIP. When the load factor LIP becomes, the control is performed so that the protection on-time ratio DR is set or the predetermined time width is equal to or less than the protection on-time ratio DR.

  According to the method for controlling the on-time width of the regenerative transistor according to the third embodiment, the regenerative power consumption process can be performed so as not to exceed the allowable value of regenerative power that can be consumed by the regenerative circuit.

  As described above, the motor control device according to the present invention is useful as a motor control device that can perform regenerative power consumption processing using a small-scale and low-capacity regenerative resistor, and in particular, a common bus. The present invention is suitable for constructing a motor control system that can apply regenerative power consumption processing by making the best use of the capacity of all the regenerative circuits by applying to the motor control system having the configuration.

1,41 Three-phase AC power supply 2,54,55 Motor controller 3,42,56 Converter circuit 4,53,67 Diode stack 5,43,57 Main circuit capacitor 6,44,60 Regenerative circuit 7,45,59 Regenerative Resistor 8, 46, 58 Regenerative transistor 9, 47, 65 Voltage type inverter 10, 52, 66 Motor 11, 48, 61 Bus voltage detection circuit 12, 49, 62 Regenerative transistor drive circuit 13, 50, 63 Inverter drive circuit 14 , 51, 64 Arithmetic unit 21 Bus voltage when regenerative power is not returned 22 Bus voltage when regenerative power is returned 23 Off voltage of regenerative transistor (bus voltage determined to turn off regenerative transistor)
24 ON voltage of regenerative transistor (bus voltage for judging that regenerative transistor is turned on)
25 Regenerative load factor 26, 28, 30 Determination load factor P Positive bus N N Negative bus DR Protection on-time ratio LIP First regenerative load factor LCP Second regenerative load factor

Claims (6)

A converter circuit for generating a bus voltage;
An inverter circuit that converts the bus voltage applied to both ends into an AC voltage of an arbitrary magnitude and frequency and supplies the AC voltage to the motor;
A regenerative circuit comprising a series circuit of a regenerative resistor and a regenerative transistor connected in parallel to the inverter circuit and applied with the bus voltage at both ends;
In the motor control device comprising: a control means for turning on the regenerative transistor to cause the regenerative resistor to consume the regenerative power when the bus voltage exceeds a predetermined value due to regenerative power from the motor.
The control means includes
The motor control device, wherein the on-time ratio of the regenerative transistor is variably controlled in accordance with a regenerative load factor which is a state of the regenerative circuit. The control means includes
2. The motor control device according to claim 1, wherein control is performed to increase an on-time ratio of the regenerative transistor when the regenerative load factor is small, and control to decrease when the regenerative load factor is large. . The control means includes
A predetermined time in which a first load factor close to an allowable value of regenerative power that can be consumed by the regenerative resistor and a second load factor smaller than the first load factor are determined, and the protection function is not activated as excessive regeneration. Set the ratio to the on-time ratio for protection of the regenerative transistor,
The on-time ratio of the regenerative transistor is continuously set to a time ratio of 100% equal to the ratio of the unit time until the regenerative load ratio reaches the second load ratio, and the regenerative load ratio is the second load ratio. When the load ratio is reduced from the 100% time ratio to the protection on-time ratio from the load ratio to the first load ratio, the regenerative load ratio becomes the first load ratio. The motor control device according to claim 1, wherein the protection on-time ratio is set to a predetermined time ratio equal to or less than the protection on-time ratio. In a motor control system in which a plurality of inverter type motor control devices are connected so that each bus is a common bus,
Each of the plurality of inverter-type motor control devices is the motor control device according to claim 1,
The control means in the plurality of motor control devices are each independently,
A motor control system, wherein the on-time ratio of the regenerative transistor is variably controlled according to a regenerative load ratio that is a state of the regenerative circuit. The control means in the plurality of motor control devices are each independently,
5. The motor control system according to claim 4, wherein control is performed to increase an on-time ratio of the regenerative transistor when the regenerative load factor is small, and control is performed to decrease when the regenerative load factor is large. . The control means in the plurality of motor control devices are each independently,
A predetermined time in which a first load factor close to an allowable value of regenerative power that can be consumed by the regenerative resistor and a second load factor smaller than the first load factor are determined, and the protection function is not activated as excessive regeneration. Set the width to the on-time ratio for protection of the regenerative transistor,
The on-time ratio of the regenerative transistor is continuously set to a time ratio of 100% equal to the ratio of the unit time until the regenerative load ratio reaches the second load ratio, and the regenerative load ratio is the second load ratio. When the load ratio is reduced from the 100% time ratio to the protection on-time ratio from the load ratio to the first load ratio, the regenerative load ratio becomes the first load ratio. The motor control system according to claim 4, wherein the protection on-time ratio is set to a predetermined time ratio equal to or less than the protection on-time ratio.

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