JP3473569B2 - Control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device which receives power from a polyphase AC power source and drives a polyphase load.

[0002]

2. Description of the Related Art Conventionally, in a device such as a compressor for an air conditioner that drives a motor by receiving electric power from a three-phase AC power source, the power source side is unbalanced (the voltage between the phases is constant. When the phenomenon of disappearing) occurs, the input current fluctuates greatly with it. This fluctuation of the input current may activate the breaker attached to the power supply side,
It may cause an unexpected motor stop.

In particular, in an environment where an air conditioner is usually installed, a power supply imbalance of about several volts often occurs, and as a result, only the current flowing through a certain phase causes the breaker capacity. And the breaker may operate.

[0004]

Therefore, in the conventional device, in order to prevent the motor from stopping even if the power supply is unbalanced, the motor should be provided with a margin of about 20 to 30% with respect to the breaker capacity. Designed to drive. In other words, the fixed margin of about 20 to 30% is a measure against the power supply imbalance, so that the operation control with a margin for the breaker capacity is always performed regardless of the occurrence of the power supply imbalance. Was configured into.

Therefore, it is difficult to say that the motor is effectively driven within the range of the breaker capacity in the related art. For example, even if an attempt is made to increase the drive capacity of the motor, the motor is driven by a current lower by about 20 to 30% than the breaker capacity. Will drive
There was a situation where it was not possible to drive the motor by making the most of the power supply.

Therefore, the present invention has been made in view of the above problems, and does not operate the breaker in a situation where there is a power supply imbalance, and the power supply power is effectively used even in such a situation. It is an object of the present invention to provide a control device capable of driving a motor.

[0007]

In order to achieve the above object, a control device (1) according to claim 1 rectifies a ripple component (Vm) obtained by rectifying an output of a polyphase AC power source (10).
The maximum value of the input current from the multi-phase AC power supply is predicted based on the above, and the multi-phase load (30) is driven by using the multi-phase AC power supply so that the maximum value is within the range of the allowable current. Is composed of.

A control device (1) according to a second aspect is the control device (1) according to the first aspect, wherein the control means (2)
0) predicts the maximum value and gives a control signal to the drive circuit (15) for driving the multi-phase load (30) so that the maximum value falls within the allowable current range. .

A control device (1) according to a third aspect is the control device (1) according to the second aspect, wherein the control means (20) performs a predetermined arithmetic process on the ripple component (Vm). It is characterized in that the maximum value is predicted by performing.

A control device (1) according to a fourth aspect is the control device (1) according to the third aspect, wherein the control means (20) performs the arithmetic processing based on the ripple component (Vm). At the time of performing, the arithmetic processing is performed by subtracting an ideal ripple voltage when the polyphase AC power source is in a balanced state from the ripple voltage (Vm).

A control device (1) according to a fifth aspect of the present invention is the control device (1) according to the third or fourth aspect, wherein the control means (20) determines the type of the multi-phase AC power source (10). It has a function of recognizing and is characterized in that the arithmetic processing is performed using a parameter according to the type.

A control device (1) according to a sixth aspect of the present invention is the control device (1) according to the third or fourth aspect, wherein the control means (20) controls the drive capacity of the polyphase load (30). It has a function of recognizing, and is characterized in that the arithmetic processing is performed using a parameter according to the driving ability.

A controller (1) according to a seventh aspect is the controller (1) according to any one of the first to sixth aspects, wherein the maximum value is in each phase of the multi-phase AC power source (30). It is characterized in that it is the maximum current of the currents flowing through.

The control device (1) according to claim 8 is the control device (1) according to any one of claims 1 to 7, wherein the ripple component (Vm) is filtered after the rectification. It is characterized by being detected.

A control device (1) according to a ninth aspect is the control device (1) according to the eighth aspect, wherein the filtering process is realized by an inductor (12) and a capacitor (13). It has a feature.

A control device (1) according to a tenth aspect of the present invention is the control device (1) according to any one of the first to ninth aspects, wherein the input when the polyphase AC power source (10) is in a balanced state. It is characterized in that the maximum value is predicted by adding the current increase amount (ΔI) when the polyphase AC power source (10) is in an unbalanced state to the current (Iin).

The control device (1) according to claim 11 is the control device (1) according to claim 10, wherein the unbalanced state is one of the inter-phase voltages of the multi-phase AC power supply (10). It is characterized by being in an unbalanced state when one interphase voltage is larger than the reference voltage and the other interphase voltage is smaller than the reference voltage.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a control device 1 according to the present embodiment, and specifically, a circuit diagram showing a motor 30 for a compressor of an air conditioner and its peripheral circuits. For example, R,
The voltage applied from the three-phase AC power supply 10 including the three phases S and T is rectified into a DC current having ripples by the diode bridge 11 having a known structure. Then, this is filtered by, for example, a choke input type filter, and a DC voltage is applied to the inverter 15. The inverter 15 is a drive circuit that performs pulse width modulation switching under the control of the control circuit 20 and supplies, for example, a three-phase alternating current to the motor 30 to drive the motor 30.

The choke input type filter is shown in FIG.
As shown in, the capacitor 13 having one end and the other end connected to the negative output end (−) of the diode bridge 11, the other end of the capacitor 13 and the positive output end (+) of the diode bridge 11. And an inductor 12 interposed between the two. The negative output terminal of the diode bridge 11 is grounded, for example.

The control circuit 20 is composed of, for example, a central processing unit, and controls the operation of the inverter 15. The control circuit 20 has three analog input ports AN0,
It is provided with AN1 and AN2, each of which is a voltage detection circuit 2
1, the voltage detection value Vm, the current detection value Im, and the peak current output from the current detection circuit 22 and the peak detection circuit 23 are input. Then, when causing the inverter 15 to perform the operation of rotating the motor 30, the input current from the three-phase AC power source 10 is predicted based on these detected values, and the inverter 15 is controlled so that it is within the allowable range of the breaker 16. Then, the motor that is the load is driven. The peak current input from the peak detection circuit 23 is used for the control circuit 20 to recognize the driving ability of the motor 30.

The voltage detection circuit 21 is composed of, for example, a filter, measures the voltage at the connection point between the inductor 12 and the capacitor 13, and outputs the ripple component of the voltage as the voltage detection value Vm. The current detection circuit 22 is composed of, for example, an average value circuit or a peak hold circuit, detects a pulsed current flowing between the negative side output end of the diode bridge 11 and the inverter 15, and outputs the average value or the like as a current detection value. Output as Im. To measure this current, for example, the negative output terminal of the diode bridge 11 and the inverter 15
A resistor 14 is inserted between the negative side input terminal (-) and the negative side input terminal (-), and the voltage drop there is measured.

In the motor control device constructed as described above, when the three-phase AC power supply 10 is in a balanced state of 200 V, that is, when the voltage between the phases is 200 V and uniform, the voltage detection value Vm is obtained. The ripple component of the applied voltage is about 5 and 6V. On the other hand, in the unbalanced state, the ripple component is about 30 to 40V.

Further, the current detection value Im detected by the current detection circuit 22 has a correlation with the input current input to the diode bridge 11 from the three-phase AC current 10. If the input current is Iin, then Iin = α · Im + β (where α and β are constants) ... In the equilibrium state of the three-phase AC power supply 10, the currents of the respective phases (R, S, T) are equal. Therefore, if the detected current value Im is obtained, the input current Iin of each phase in the equilibrium state can be predicted.

On the other hand, in the unbalanced state, the currents of the R, S and T phases are not uniform. Therefore, the control circuit 20
Is predicted from the ripple component obtained as the voltage detection value Vm. The prediction is based on the assumption that the equilibrium state has been changed to an unbalanced state.
It is performed by estimating I from the ripple component and adding the current increment to the input current Iin in the equilibrium state.

Specifically, it has been experimentally recognized that the current increment ΔI of the phase exhibiting the maximum current in the unbalanced state affects the ripple component detection result obtained as the voltage detection value Vm. The ripple component tends to increase as the increase ΔI increases, while the ripple component tends to decrease as the current increase ΔI decreases. Therefore, the current increase ΔI of the phase showing the maximum current in the unbalanced state can be expressed as ΔI = a · Vm + b (where a and b are constants).

When the maximum input current of the currents of the respective phases in the unbalanced state is Imax, the input current Imax is obtained by adding the current increase amount ΔI in the unbalanced state to the input current Iin in the balanced state. , Imax = Iin + ΔI = α · Im + a · Vm + β + b.

Each parameter α, a, β which is a constant
+ B is experimentally obtained in advance, and the control circuit 20 substitutes the voltage detection value Vm and the current detection value Im obtained from the voltage detection circuit 21 and the current detection circuit 22 into the above correction formula to perform the arithmetic processing. Maximum current Ima of the currents flowing in the respective phases when the three-phase AC power supply 10 is in an unbalanced state
It becomes possible to predict x.

When the three-phase AC power supply 10 is in an unbalanced state, the interphase voltage of one of the three phases of R, S, and T is higher than the reference voltage (for example, 200V), and the interphase voltage of the other two phases. A first unbalanced state that is smaller than the reference voltage, one interphase voltage is greater than the reference voltage, another one interphase voltage is equal to the reference voltage, and another one interphase voltage is less than the reference voltage. There are three aspects of the second unbalanced state and the third unbalanced state in which the two interphase voltages are larger than the reference voltage and the other one interphase voltage is smaller than the reference voltage.

Here, the unbalance rate is 2% (for example, the reference voltage is 2
00 V and the inter-phase voltage has a variation of about ± 4 V with respect to the reference voltage), an experiment is performed on the above three aspects, and each parameter of the correction formula in the case of the first unbalanced state is obtained. If so, the maximum current Imax can be predicted by using the correction formula even in other unbalanced states. That is, the correction amount for predicting the maximum current Imax is the largest in the first unbalanced state among the above three modes, so the maximum current Imax is predicted using the correction formula in the other unbalanced state. However, the predicted value does not actually fall below the current value flowing from the three-phase AC power supply 10 through each phase.

Therefore, among the above three modes, the parameters of the above-mentioned correction equation are set for the first unbalanced state when one interphase voltage is larger than the reference voltage and the other two interphase voltages are smaller than the reference voltage. The maximum current I
If max is controlled within the allowable range of the breaker 16, the inverter 15 can be controlled and the motor 30 can be driven without operating the breaker 16 even in the other second and third unbalanced states. .

FIG. 2 shows the maximum current Imax in this embodiment.
It is a figure which shows the prediction experiment result of. The horizontal axis in the graph of FIG. 2 is actually measured by an ammeter inserted between the three-phase AC power supply 10 and the diode bridge 11, and the first unbalanced under the power supply unbalance rate of 2%. The state is reproduced, and the input maximum current, which is the maximum current of the R, S, and T phases, is shown when the output frequency is increased while the motor 30 is driven under the same conditions as in the balanced state. Further, the vertical axis represents the detected current value Im input to the control circuit 20 and the current value of the maximum current Imax derived by the control circuit 20 as a result of the arithmetic processing based on the above correction formula.

As shown in FIG. 2, for example, the output frequency 104H
When the motor 30 is driven by z, the detected current value Im input to the control circuit 20 is 16.1A, although the maximum input current actually input from the three-phase AC power supply 10 is 21.1A. . Further, when driven at an output frequency of 128 Hz, the current detection value Im input to the control circuit 20 is 19.50 even though the maximum input current actually input from the three-phase AC power supply 10 is 25.0 A. 2A. Further, when driven at an output frequency of 216 Hz, the detected current value Im input to the control circuit 20 is 24. although the maximum input current actually input from the three-phase AC power supply 10 is 31.6 A. 1A. In any of these cases, the current detection value Im is actually the three-phase AC power supply 10
The value is smaller than the maximum current input from. Therefore, for example, in the case of a configuration in which 30 A is set as the current at which the breaker 16 operates, the output frequency is 21
When reaching 6 Hz, the current detection value I detected by the control circuit 20
Even if m is less than 30 A, the breaker 16 operates and the entire device stops.

On the other hand, in this embodiment, when the maximum current Imax is predicted by correcting the current detection value Im based on the ripple component obtained as the voltage detection value Vm based on the above correction formula, the maximum current Imax shown in FIG. As shown in the graph, it is possible to predict the maximum current that substantially matches the actual maximum input current. Therefore, for example, it can be predicted that the output frequency will exceed 30 A at the stage of the output frequency of 216 Hz. Therefore, even when the control circuit 20 increases the output frequency, the frequency that can be driven by the current within the range permitted by the breaker 16 A control signal for performing the operation can be given to the inverter 15.

Therefore, if the current value at which the breaker 16 operates is set in advance in the control circuit 20, the control circuit 20 outputs the voltage from the three-phase AC power source 10 based on the voltage detection value Vm and the current detection value Im. Since the maximum input current is predicted and the motor 15 is driven by controlling the inverter 15 so that the predicted maximum current is within the allowable range, the breaker 16 is not operated even in the unbalanced state, and Even under such a condition, the motor 30 can be driven by effectively utilizing the power supply within the range allowed by the breaker 16. In other words, it is possible to perform drive control that reduces the operating capacity of the motor 30 before the breaker 16 operates.

In the above correction equation, the maximum current I is calculated by using the voltage detection value Vm input to the control circuit 20 as it is.
Although the method of predicting max has been described, even when the three-phase AC power supply 10 is in a balanced state, a ripple component of about 5 and 6 V (which is referred to as an ideal ripple voltage Vr) is detected as the voltage detection value Vm. To be done. Therefore, in the unbalanced state, the correction formula is a correction formula for appropriately predicting the maximum current. However, when the same process is performed in the balanced state, the ripple component in the balanced state is not zero. As a result, the input current cannot be predicted properly.

In order to avoid this, when obtaining each parameter of the above-mentioned correction formula, the ideal ripple voltage (Vr) is previously calculated from the voltage detection value Vm by Vm '= Vm-Vr.
= 5 to 6 V) is subtracted to obtain the ripple voltage Vr, the ripple voltage Vr is used instead of the voltage detection value Vm to obtain each parameter, and when the control circuit 20 performs the actual control, Based on the above equation, the voltage detection circuit 21
A ripple current Vm ′ obtained by subtracting the ideal ripple voltage Vr from the input voltage detection value Vm is used instead of Vm in the above correction formula to perform a calculation process to predict the maximum current and control the motor drive. Is preferred. With such a configuration, an appropriate calculation result can be obtained regardless of whether the three-phase AC power supply 10 is in a balanced state or an unbalanced state, and the input current can always be accurately predicted. Become.

Further, in the control device 1 of this embodiment, the alternating current from the three-phase alternating current power source 10 is rectified by the diode bridge 11, and after the rectification, it is subjected to a filtering process to detect the ripple voltage. . Then, the filtering process is performed by the filter unit realized by the inductor 12 and the capacitor 13. When the capacitor 13 is used for many years, it tends to change over time and its capacitance tends to decrease. Therefore, each parameter applied to the above correction formula becomes a parameter for predicting an appropriate maximum current at the time of manufacturing the control device 1, but as the capacitance of the capacitor 13 decreases due to subsequent use. It may not be the optimal parameter.

However, as long as the maximum current is predicted by using the above-mentioned correction formula, even if the capacitance of the capacitor 13 deteriorates due to aging and each parameter is not the optimum value, the input from the three-phase AC power supply 10 is actually made. Since the predicted maximum current value is estimated to be larger than the predicted current value, the breaker does not operate, and there is no problem.

Further, in the above description, it was not particularly mentioned whether the input frequency from the three-phase AC power source 10 was 50 Hz or 60 Hz, but if they are different, it is detected as the voltage detection value Vm. Since the ripple components show different tendencies, the parameters (constants a and b) of the above correction equation also differ.

Therefore, the control circuit 20 controls the type of the three-phase AC power source 10, that is, the input frequencies are 50 Hz and 60 Hz.
It is desirable to implement such a configuration that it has a function of discriminating which one of the above, and to select the optimum parameter based on the discrimination result to predict the maximum current Imax based on the correction formula. Specifically, when the control device 1 is installed, by connecting or disconnecting a jumper wire (not shown) in the control circuit 20 or switching a dip switch, the control circuit 20 causes the three-phase AC power supply 10 to operate. Can recognize the type of. And by realizing in this way, the maximum current Imax can be always predicted appropriately according to the environment where the control device 1 is installed, and the capacity of the motor 30 can be maximized without operating the breaker 16. It becomes possible to drive to operate.

Further, even when the driving capability of the compressor is different, the parameters are different, so that the control circuit 20 recognizes the driving capability of the compressor based on the peak current from the peak detection circuit 23. If the optimum parameter is selected according to the recognition result and the maximum current Imax is predicted, it is possible to accurately predict the maximum current based on the driving capability of the compressor.

As described above, according to the control device 1 of this embodiment, the maximum value of the input current from the three-phase AC power source 10 is
It is configured to make a prediction based on the rectified ripple component. On the other hand, each phase R, S, of the three-phase AC power supply 10
Even if the current flowing through T is directly detected, the operating capacity of the motor 30 can be reduced before the breaker operates. In this case, the number of required sensors increases and the control device There is a possibility of increasing the size and increasing the cost.

Since the control device 1 described in the present embodiment can know the maximum value of the input current with the minimum number of sensors, the control device 1 can be downsized and the cost thereof can be reduced. It also makes it possible to reduce the size and cost of the overall harmony machine.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above description.

For example, in the above description, the case where the power supply is a three-phase AC power supply has been described, but the present invention is not limited to this, and any multi-phase AC power supply that may cause an unbalanced state may be used. .

The load driven by the inverter 15, which is a drive circuit, is not limited to the motor.

[0048]

As described above, according to claims 1 to 1.
According to the first aspect of the present invention, the maximum value of the input current from the polyphase AC power supply is predicted based on the ripple component, and the polyphase AC power supply is used so that the maximum value is within the allowable current range. Since the load is driven, for example, the drive state of the load can be lowered before the allowable current range is exceeded. Therefore, it is possible to drive the load without operating the breaker even in a situation where the polyphase AC power source has a power source imbalance, and to effectively utilize the power source even in such a situation.

Further, in particular, according to the invention of claim 4, the maximum value of the input current can be appropriately predicted regardless of whether the multi-phase AC power supply is in a balanced state or an unbalanced state, and under any circumstances. Also, it is possible to drive the load without operating the breaker and by effectively using the power supply power.

Further, in particular, according to the invention of claim 5, since the arithmetic processing is performed by using the parameter according to the kind of the multi-phase AC power source, it is always appropriate depending on the installation environment of the control device. The maximum value of the input current can be predicted.

Further, in particular, according to the invention of claim 6, since the arithmetic processing is performed by using the parameter according to the driving ability of the multi-phase load, the control device is adapted to the applied load. The maximum value of the input current can always be appropriately predicted.

According to the seventh aspect of the invention, the maximum current that causes the breaker to operate can be appropriately predicted, and the load can be driven without operating the breaker.

Further, according to the invention of claim 9, it is possible to drive the load without operating the breaker even when the capacitor changes with time.

According to the tenth aspect of the present invention, the current increment when the polyphase AC power source is in the unbalanced state is added to the input current when the polyphase AC power source is in the balanced state. Is configured to predict the maximum value, the maximum current can be predicted without directly measuring the input current.

According to the eleventh aspect of the invention, among the inter-phase voltages of the multi-phase AC power source, one inter-phase voltage is higher than the reference voltage and the other inter-phase voltage is lower than the reference voltage. Since the increase in current in the unbalanced state is added to the input current in the balanced state, the load can be driven without operating the breaker even in other unbalanced states.

[Brief description of drawings]

FIG. 1 is a diagram showing a control device.

FIG. 2 is a diagram showing a result of a maximum current prediction experiment.

[Explanation of symbols]

1 control device 10 Three-phase AC power supply 11 diode bridge 12 inductors 13 capacitors 15 Inverter (drive circuit) 20 Control circuit (control means) 21 Voltage detection circuit 22 Current detection circuit 30 motor (load) Vm voltage detection value (ripple component) Im current detection value

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02M 7/48 G02J 3/26

Claims (11)

(57) [Claims] 1. A maximum value of an input current from the polyphase AC power supply is predicted based on a ripple component (Vm) obtained by rectifying an output of the polyphase AC power supply (10), and the maximum value is an allowable current. A control device (1) for driving a polyphase load (30) by using the polyphase AC power supply so as to be within the range. 2. The control device (1) according to claim 1, wherein the control means (20) predicts the maximum value, and
A control device for applying a control signal to the drive circuit (15) for driving the multi-phase load (30) such that the maximum value is within an allowable current range. 3. The control device (1) according to claim 2, wherein the control means (20) performs a predetermined arithmetic process on the ripple component (Vm) to predict the maximum value. A control device characterized by performing. 4. The control device (1) according to claim 3, wherein when the control means (20) performs the arithmetic processing based on the ripple component (Vm), the multi-phase AC power supply is balanced. A control device, wherein the ideal ripple voltage in a state is subtracted from a ripple voltage (Vm) to perform the arithmetic processing. 5. The control device (1) according to claim 3 or 4.
In the control device, the control means (20) has a function of recognizing the type of the multi-phase AC power source (10) and performs the arithmetic processing using a parameter according to the type. 6. The control device (1) according to claim 3 or 4.
In the control device, the control means (20) has a function of recognizing the driving capability of the multi-phase load (30) and performs the arithmetic processing using a parameter according to the driving capability. . 7. The control device (1) according to any one of claims 1 to 6, wherein the maximum value is the maximum current of the currents flowing through the respective phases of the multi-phase AC power supply (30). A control device characterized by. 8. The control device (1) according to claim 1, wherein the ripple component (Vm) is detected by a filtering process after the rectification. 9. The control device (1) according to claim 8, wherein the filtering process includes an inductor (12) and a capacitor (1).
3) A control device which is realized by 10. The control device (1) according to any one of claims 1 to 9, wherein the multi-phase AC power supply (10) has an input current (Iin) when the multi-phase AC power supply (10) is in a balanced state. 10. The control device characterized in that the maximum value is predicted by adding a current increase amount (ΔI) when 10) is in an unbalanced state. 11. The control device (1) according to claim 10, wherein, in the unbalanced state, one of the interphase voltages of the multiphase AC power supply (10) is larger than a reference voltage, Also, the control device is in an unbalanced state when the other interphase voltage is smaller than the reference voltage.