JP2000253686A - Power regenerating circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller where the tolerance range for not letting an overcurrent flow to the switching transistor of a regenerative circuit at power regeneration can be set widely. SOLUTION: This power regenerating circuit is composed of a regenerative circuit part 3 which is constituted of a bridge-wired switching element and converts DC power into AC power, a line voltage detector 4 which is connected to the AC power source and output the line voltage of an AC power source in its own combination of each phase, a phase application phase decider 5 which decides the phase to be supplied with power of the regenerative circuit part, based on the line voltage, a zero cross judger 6 which outputs a commutation signal when the absolute value of the line voltage falls under the preset voltage value, a timer 8 which outputs a preset period regeneration stop command after the commutation signal is inputted, and a control signal generator 9 which generates a control signal to control it so that the regenerative circuit may perform the power regenerative actin, based on the current application command, when a regenerative action command is inputted and a regeneration stop command is off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power regeneration circuit used for a motor control device using a power regeneration system as a braking system.

[0002]

2. Description of the Related Art FIG. 3 shows a configuration example of a conventional power regeneration circuit applied to a motor control device using a power regeneration system as a braking system. In FIG.
Reference numeral 1 denotes an AC power supply. Reference numeral 2 denotes a converter circuit, which is composed of six bridge-connected diodes and is connected to the AC power supply 1, the regenerative circuit unit 3, and the smoothing capacitor 13, and converts AC power supplied from the AC power supply 1 into DC power. Convert. Reference numeral 3 denotes a regenerative circuit unit, which is configured by a bridge connection of six transistors 20, 21, 22, 23, 24, and 25, and is connected to the AC power supply 1, the converter circuit 2, and the smoothing capacitor 13, and includes a control unit described later. Signal 11
4, 115, 116, 117, 118 and 119, the transistors 20 to 25 are switched to convert DC power into AC power. Reference numeral 7 denotes an energized phase determining unit, which is connected to the AC power supply 1 and which is energized phase command 103,
It outputs 104, 105, 106, 107, 108 and a commutation signal 109. 8 is a timer, which is a commutation signal 10
Regeneration stop command 1 for a preset period after 9 is input
10 is turned on, and the regeneration stop command 110 is turned off in other periods. Reference numeral 9 denotes a control signal generation unit, which receives control signals 114 and 115 at a timing described later based on the energized phase commands 103, 104, 105, 106, 107 and 108 when the regeneration operation command 113 is input and the regeneration stop command 110 is off. , 1
16, 117, 118 and 119 are output. When the regeneration operation command 113 is not input and when the regeneration stop command 110 is on, the control signals 114, 115, 1
16, 117, 118 and 119 are all turned off. An AC voltage detector 10 is connected to the AC power supply 1,
A peak value 111 of the AC power supply voltage is output. A DC voltage detector 11 is connected to the smoothing capacitor 13 and outputs a DC circuit voltage value 112. Reference numeral 12 denotes a regenerative operation commander, to which a peak value 111 of the AC power supply voltage and a DC circuit voltage value 112 are inputted, and that the DC circuit voltage value 112 is equal to or more than a value set in advance from the peak value 111 of the three-phase AC power supply voltage When it becomes larger, a regeneration operation command 113 is output. A smoothing capacitor 13 smoothes the DC circuit voltage. Reference numeral 14 denotes an inverter circuit, which performs required DC / AC conversion on the DC power supplied from the smoothing capacitor 13 and drives the AC motor 15 with driving power.

The motor control device having such a configuration converts AC power into DC power once in the converter circuit 2 when the AC motor 15 is driven at a constant speed or accelerated.
After smoothing by the smoothing capacitor 13, DC power is supplied to the inverter circuit 14 to obtain an AC voltage having a variable frequency and drive the AC motor 15. When braking the AC motor 15 to reduce the motor speed, the rotational energy of the AC motor 15 is converted into DC power by the inverter circuit 14. Accordingly, when the DC circuit voltage increases and the DC circuit voltage value 112 becomes larger than the peak value 111 of the AC power supply voltage by a predetermined value or more, the regenerative operation command 1
13 is output from the regenerative operation command device 12. When the regenerative operation command 113 is input to the control signal generator 9,
DC power is converted into AC power by the operation described below. In this way, the rotational energy of the AC motor 15 is regenerated to the AC power supply 1, and the AC motor 15 is quickly decelerated.

Here, the commutation signal 109 and the energized phase command 10
3, 104, 105, 106, 107, 108 and control signals 114, 115, 116, 117, 118, 119
4 will be described with an example in which the line voltage of the AC power supply 1 changes as shown in FIG. Where R-
The S-phase voltage is a line voltage between the R-phase and the S-phase based on the S-phase. The other RT phase and ST phase have the same meaning. The energizing phase determination unit 7 determines the RS phase, the RT phase, the ST phase,
From the SR phase, the TR phase, the TS phase and the six types of line voltages, the phase having the highest instantaneous value at each timing is determined as the energized phase. For example, at the timing when the instantaneous value of the RS phase is the highest, the RS phase is determined as the energized phase.

Next, the positive side of the DC circuit is connected to the AC power supply 1 through the transistor connected to the positive side of the energized phase determined in this way, and connected to the negative side of the energized phase. Energized phase commands 103, 104, 105, 106, 107, and 108 are output from the energized phase determination unit 7 so that the negative of the DC circuit is connected to the AC power supply 1 through the transistor. For example, at the timing when the RS phase is the energized phase, the transistor 20 connected to the R phase of the AC power supply 1 and the plus side of the DC circuit in the regenerative circuit unit 3, the S phase of the AC power supply 1 and the DC circuit An energization phase command is output so that the transistor 23 connected to the minus side is turned on. The energized phase command for turning on the transistor 20 is the energized phase command 103, and the energized phase command for turning on the transistor 23 is the energized phase command 10
6. Therefore, at this timing, the energized phase command 10
3, 106 are output. Further, the correspondence between the other transistors and the energized phase command is as follows:
04, the transistor 22 is a conduction phase command 105, the transistor 24 is a conduction phase command 107, and the transistor 25 is a conduction phase command.

The commutation signal 109 is output from the energized phase determining section 7 when the energized phase is switched as shown in FIG. On the other hand, the regeneration stop command 110 is turned on for a preset period after the commutation signal 109 is input to the timer 8, and is turned off in other periods.

The control signals 114, 115, 116, 11
With respect to 7, 118 and 119, the transistor 20 is turned on when the control signal 114 is turned on, the transistor 21 is turned on when the control signal 115 is turned on, the transistor 22 is turned on when the control signal 116 is turned on, and the control signal 117 is turned on.
Turns on, the transistor 23 turns on, and the control signal 11
8 turns on the transistor 24 and the control signal 1
The transistor 19 is configured to be turned on when 19 is turned on. Therefore, the control signal 114 is the regenerative operation command 1
13 is input to the control signal generator 9 and the regeneration stop command 1
When 10 is off, it turns on in accordance with the energized phase command 103. That is, as shown in FIG.
Is input, it is turned on except during the period immediately after the switching of the energized phase during the period in which the instantaneous values of the RS phase and the RT phase are the highest. When the control signal 114 is turned on, the transistor 20 is turned on, and the R phase of the AC power supply 1 is connected to the positive side of the DC circuit. Other control signals and transistors perform the same operation, and the relationship between the line voltage and the ON timing of each control signal, that is, the ON timing of each transistor, is as shown in FIG.

By performing such an operation, when the regenerative operation command 113 is input, the phase having the highest instantaneous value of the line voltage of the AC power supply 1 and the DC circuit are connected with the same polarity. Incidentally, the regenerative operation command 113 is output from the regenerative operation commander 12 when the DC circuit voltage value 112 becomes larger than a predetermined value from the peak value 111 of the AC power supply voltage. As described above, the AC power supply 1
And the DC circuit are connected at a timing determined by the AC power supply phase, a current flows from the DC circuit to the AC power supply 1, and DC power is converted into AC power. The reason why the DC circuit is connected to the phase having the highest instantaneous value of the line voltage of the AC power supply 1 is that an excessive current is generated by setting the potential difference between the AC power supply 1 and the DC circuit to a certain value or less. This is to prevent shedding.

By performing the above operation, when the phase having the highest instantaneous value of the line voltage of the AC power supply 1 is switched, the regenerative operation is stopped for a certain period. This is because, when the phase at which the instantaneous value of the line voltage of the AC power supply 1 is the highest, that is, the energized phase is switched, the transistor connecting the AC power supply 1 and the DC circuit is switched. This keeps the current from flowing. That is, when the transistor is turned off, the current continues to flow through the freewheeling diode of the transistor on the opposite arm to the transistor that has been turned on until the energy stored in the inductance existing in the circuit is consumed. Therefore, when the transistor of the next energized phase is turned on at the timing of switching of the energized phase, the AC power supply 1 is short-circuited through the free wheel diode and the transistor which are turned on at this time, an excessive current flows and the transistor is destroyed. . Therefore, by turning off all the transistors during the freewheel period after the switching of the energized phase, it is possible to prevent an excessive current from flowing due to the above-mentioned short-circuit and to destroy the transistors. Note that timer 8
Is set to a value at which the regenerative operation can be stopped during the freewheel period in consideration of the use conditions of the control device.

Here, the operation of the current and the voltage when the energized phase is switched will be described by taking the switching from the TS phase to the RS phase as an example. First, when the energized phase is the TS phase, the transistors 23 and 24 are on, a current flows from the DC circuit to the AC power supply 1 in the direction shown in FIG. 5, and the DC power is regenerated and converted into AC power. Have been. Next, when the RS phase voltage rises and the potential of the R phase becomes higher than the T phase, the transistor 2
Since 4 is on, the freewheeling diode of transistor 20 is connected through transistor 24 to the T phase. Therefore, the freewheel diode of the transistor 20 is turned on with a forward bias state. For this reason, the R-phase and T-phase of the AC power supply 1 are short-circuited by the freewheel diode of the transistor 20 and the transistor 24, and the power supply short-circuit current Is flows in the direction shown in FIG. Since the R-phase and T-phase of the AC power supply 1 are short-circuited by the regenerative circuit unit 3,
The RS phase voltage that has risen as shown in FIG. 7 becomes equal to the TS phase voltage. Therefore, the energized phase determination unit 7 cannot determine the switching of the energized phase, and continues the regenerative operation with the TS phase as the energized phase. During the period in which the regenerative operation continues even after the original energization period, the voltage determined by the ratio of the power impedance present in the AC power supply 1 to the wiring impedance of the power regeneration circuit existing between the transistors and the like is determined as the energized phase. Input to the unit 7. The commutation signal 109 is output at a point in time when the RS phase voltage becomes larger than the TS phase voltage until the energized phase determination unit 7 can determine the switching of the energized phase due to the increase in the RT phase voltage. Then, the regenerative operation is stopped by the operation described above. When the regenerative operation is stopped, the transistor 24 is turned off and the short-circuit path is cut off, so that the input voltage of the energized phase determination unit 7 becomes equal to the voltage of the AC power supply 1.

As described above, the time point at which the energized phase determination unit 7 determines the switching of the energized phase is determined by the ratio of the power impedance present in the AC power supply 1 to the wiring impedance of the power regenerating circuit. In the lower part, switching of the energized phase is determined before an abnormality occurs. However, when used with an AC power supply with a large power supply impedance,
The period during which the regenerative operation continues even after the original energization period becomes longer, the potential difference between the AC power supply and the DC circuit increases,
Excessive current flows and the transistor is destroyed.

Even when a switching element such as a thyristor having no freewheeling diode is used in the regenerative circuit section, when the converter circuit is configured by a bridge-connected diode, the same operation as the freewheeling diode in the above description is performed. Is performed by the diode of the converter circuit.

For this reason, the operating conditions of the power regeneration circuit in which a diode is connected in anti-parallel to the switching element constituting the regeneration circuit section are limited by the magnitude of the power supply impedance.

What has been described so far is a power regeneration circuit that detects a voltage of each phase of the AC power supply circuit, determines a phase to be energized by the power conversion unit, and performs a regeneration operation. Although voltage control is performed, current flowing from the DC circuit to the AC power supply circuit is not controlled. In addition, there is a high-grade power regeneration circuit that performs current feedback control from the DC circuit to the AC power supply circuit. Since the current value is constantly controlled, an excessive current flows and the switching element used is destroyed. Nothing. However, processing or configuration becomes very complicated as compared with a power regeneration circuit using only voltage control.

[0015]

As described above, in the prior art motor control apparatus using a power regeneration circuit in which only a voltage control is performed and a diode is connected in anti-parallel with a switching element constituting a regeneration circuit unit in a reverse manner. However, there is a drawback that the use conditions are limited by the magnitude of the power supply impedance. For this reason, there is a problem that a motor control device using a power regeneration circuit having the same processing or configuration as the current state cannot have a wide allowable range of operating conditions that can guarantee that the control device operates safely. The present invention has been made in view of the above-described problems, and an object of the present invention is to use a power regeneration circuit having the same simple processing or configuration as the power regeneration circuit in the related art to achieve a wide range of use conditions. An object of the present invention is to provide a motor control device having an allowable range.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a regenerative circuit unit which is composed of bridge-connected switching elements and converts DC power into AC power, and a regenerative circuit unit connected to an AC power source for each input phase. A line voltage detector that outputs a line voltage of an AC power supply in combination, an energized phase determining unit that determines an energized phase of the regenerative circuit unit based on the line voltage and outputs an energized phase command, A zero-crossing determiner that outputs a commutation signal when the absolute value of the inter-voltage falls below a preset voltage value, and after the commutation signal is input, outputs a regeneration stop command for a preset period. And a control signal generating unit for generating a control signal for controlling the regenerative circuit unit to perform a power regenerating operation based on the energized phase command when the regenerative operation command is input and the regenerative stop command is off. It is achieved by using a power regeneration circuit according to claim Rukoto.

[0017]

According to the present invention, the regenerative operation is stopped when the absolute value of the line voltage of the AC power supply becomes equal to or lower than a preset voltage value. The energized phase determining unit can determine the switching of the energized phase at a timing according to the voltage of the AC power supply regardless of the magnitude of the power supply impedance without turning on the diode.

[0018]

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a motor control device using a power regeneration system as a braking system using a power regeneration circuit according to the present invention.
Reference numeral 4 denotes a line voltage detector, which is connected to the AC power supply 1 and outputs three line voltages 100, 101, and 102 in combination with the input phases. Reference numeral 5 denotes an energized phase determination unit which receives input line voltages 100, 101, and 10
2, the energized phase commands 103, 104, 105, 1 at the same timing as the energized phase determination unit in the prior art described above.
06, 107 and 108 are output. Reference numeral 6 denotes a zero-crossing determiner, which has input line voltages 100, 101, and 102.
When the absolute value of is smaller than or equal to a preset voltage value V, a commutation signal 109 is output.

In FIG. 1, a converter circuit 2, a regenerative circuit 3, a timer 8, a control signal generator 9, an AC voltage detector 10 other than the line voltage detector 4, the energized phase determiner 5, and the zero-cross determiner 6. The functions of the DC voltage detector 11, the regenerative operation commander 12, the smoothing capacitor 13, the inverter circuit 14, and the AC motor 15 are the same as those of the conventional device of FIG. 3, and the components having the same reference numerals have the same functions.

Next, FIG. 2 shows the line voltages 100, 101, 102 and the commutation signal 1 in the motor control device shown in FIG.
It is a figure showing an example of the relation of 09. In the motor control device having such a configuration, when the regenerative operation command 113 is input to the control signal generator 9 and the regenerative operation is performed, one of the absolute values of the line voltages 100, 101, and 102 is set in advance. When the voltage value becomes equal to or lower than the current voltage value V, the zero-crossing determiner 6 outputs a commutation signal 109. The functions of the regenerative circuit 3, the timer 8, and the control signal generator 9 are the same as those of the conventional device of FIG. 3, so that when the commutation signal 109 is input to the timer 8, all the transistors 20, 21, 22,
23, 24 and 25 are turned off, and the regenerative operation is stopped for a certain period. Therefore, all the transistors are turned off before the freewheeling diodes of the transistors enter the forward bias state, so that the freewheeling diodes do not turn on. For this reason, the energized phase determination unit 5 determines the switching of the energized phase at a timing according to the voltage of the AC power supply 1 irrespective of the magnitude of the power supply impedance.

As described above, in the present embodiment, the commutation signal 109 is output when the absolute values of the input line voltages 100, 101, and 102 become equal to or less than a preset voltage value V. By providing the zero-cross determiner 6, the regenerative operation is stopped when the line voltage of the AC power supply becomes equal to or less than a preset voltage value V, so that the freewheel diode of the transistor does not turn on and the power supply impedance is reduced. Irrespective of the size of the AC power supply 1, the energized phase determining unit 5 determines the switching of the energized phase at a timing corresponding to the voltage of the AC power supply 1, and can widen the allowable range of the use condition.

As described above, according to the present embodiment, the allowable range of use conditions can be widened with a simple configuration and processing almost equivalent to those of the conventional apparatus shown in FIG.

[0023]

As described above, according to the power regeneration circuit of the present invention, a line voltage detector connected to an AC power supply and outputting a line voltage of the AC power supply in a combination of each input phase, When the absolute value of the line voltage becomes equal to or less than a preset voltage value, by using a power regeneration circuit including a zero-crossing determiner that outputs a commutation signal, the power regeneration circuit in the related art is simple and equivalent. In the processing or configuration, the energized phase determination unit can determine the switching of the energized phase at a timing according to the voltage of the AC power supply regardless of the magnitude of the power supply impedance, so that the motor control device has a wide range of allowable usage conditions. Can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a motor control device using a power regeneration system as a braking system using a power regeneration circuit according to the present invention.

FIG. 2 is a diagram illustrating an example of a relationship between a line voltage and a commutation signal of a three-phase AC power supply circuit in the power regeneration circuit according to the present invention illustrated in FIG.

FIG. 3 is a configuration diagram of a motor control device using a power regeneration system as a braking system using a conventional power regeneration circuit.

FIG. 4 is a circuit diagram of the conventional power regeneration circuit shown in FIG.
Phase line power supply circuit line voltage, commutation signal, regeneration stop command,
FIG. 4 is a diagram illustrating an example of a relationship between a conduction phase command and a control signal.

5 is a diagram illustrating an example of a current flow in a normal regenerative state in the conventional power regeneration circuit illustrated in FIG. 3;

6 is a diagram showing an example of a flow of a power supply short-circuit current Is generated at the time of switching of a conduction phase in the conventional power regeneration circuit shown in FIG.

7 is a diagram illustrating an example of an input voltage of a conduction phase determination unit in the conventional power regeneration circuit illustrated in FIG. 3;

[Explanation of symbols]

1 AC power supply, 2 converter circuit, 3 regenerative circuit section,
4 Line voltage detector, 5 energized phase determining unit, 6 zero crossing determiner, 7 energized phase determining unit, 8 timer, 9 control signal generator, 10 AC voltage detector, 11 DC voltage detector, 12 regenerative operation commander , 13 smoothing capacitor,
14 Inverter circuit, 15 AC motor.

Claims (1)

[Claims] An electric power regenerating circuit for performing a power regenerating operation from a DC circuit to an AC power supply circuit in response to a regenerative operation command from the outside, wherein the regenerative circuit unit is constituted by a bridge-connected switching element and converts DC power into AC power. A line voltage detector that is connected to an AC power supply and outputs a line voltage of the AC power supply in combination with each of the input phases; and determines a phase to be energized in the regenerative circuit unit based on the line voltage. An energized phase determining unit that outputs an energized phase command; a zero-crossing determiner that outputs a commutation signal when an absolute value of the line voltage becomes equal to or less than a preset voltage value; After that, a timer for outputting a regeneration stop command for a preset period, and when the regeneration operation command is input and the regeneration stop command is off, the regeneration circuit unit is turned on based on the energization phase command. A power regeneration circuit, comprising: a control signal generation unit that generates a control signal for controlling power regeneration operation.