JP2002153073A - Controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive a load without operation of a circuit breaker under the condition where a multi-phase AC power supply is unbalanced by effectively using an electrical power of the power supply even in such condition. SOLUTION: A control circuit 20 estimates the input maximum current under the condition that a 3-phase AC power supply 10 is unbalanced, by executing a predetermined calculation based on a ripple voltage obtained as a voltage detected value Vm after the rectification and a current detected value Im as a current value flowing into a resistor 14. A control signal is applied to an inverter 15 to control the estimated maximum current within the allowable range of the circuit breaker in order to drive a motor 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for driving a polyphase load by receiving power from a polyphase AC power supply.

[0002]

2. Description of the Related Art Conventionally, in a device such as a compressor for an air conditioner which drives a motor by receiving power supply from a three-phase AC power source, a power source is unbalanced (a voltage between each phase is constant). Occurs, the input current greatly fluctuates accordingly. This fluctuation of the input current may activate the breaker mounted on the power supply side,
It may cause unexpected motor stop.

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

[0004]

Therefore, in the conventional device, in order to prevent the motor from stopping even if the power supply becomes unbalanced, the motor is required to have 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, and the operation control is always performed with an allowance for the breaker capacity regardless of the occurrence of the power supply imbalance. Was configured to.

[0005] For this reason, it is difficult to say that the motor is effectively driven within the range of the breaker capacity. For example, even if an attempt is made to increase the driving capability of the motor, the motor is driven at a current lower by about 20 to 30% than the breaker capacity. Will be driven,
There was a situation where it was not possible to drive the motor with the maximum use of the power supply power.

Accordingly, the present invention has been made in view of the above-mentioned problems, and does not operate a breaker in a situation where power supply is unbalanced, and effectively utilizes power supply power in such a situation. It is another 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 includes a ripple component (Vm) obtained by rectifying an output of a polyphase AC power supply (10).
The maximum value of the input current from the polyphase AC power supply is predicted based on It is composed of

[0008] A control device (1) according to claim 2 is the control device (1) according to claim 1, 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) such that the maximum value falls within a range of an allowable current. .

According to a third aspect of the present invention, in the control device (1) according to the second aspect, the control means (20) performs a predetermined arithmetic processing on the ripple component (Vm). Is performed, the maximum value is predicted.

According to a fourth aspect of the present invention, in the control device (1) according to the third aspect, the control means (20) performs the arithmetic processing based on the ripple component (Vm). In performing the calculation, the arithmetic processing is performed by subtracting an ideal ripple voltage when the polyphase AC power supply is in a balanced state from a ripple voltage (Vm).

According to a fifth aspect of the present invention, in the control device (1) according to the third or fourth aspect, the control means (20) controls the type of the polyphase AC power supply (10). It has a recognizing function, and is characterized in that the arithmetic processing is performed using parameters corresponding to the type.

A control device (1) according to claim 6 is the control device (1) according to claim 3 or 4, wherein the control means (20) controls the driving capability of the polyphase load (30). It has a function of recognizing, and performs the arithmetic processing using a parameter corresponding to the driving ability.

According to a seventh aspect of the present invention, in the control device (1) according to any one of the first to sixth aspects, the maximum value corresponds to each phase of the polyphase AC power supply (30). Is the maximum current of the currents flowing through.

According to an eighth aspect of the present invention, in the control device (1) according to any one of the first to seventh aspects, the ripple component (Vm) is subjected to a filtering process after the rectification. It is characterized by being detected.

According to a ninth aspect of the present invention, in the control device (1) according to the eighth aspect, the filtering is realized by an inductor (12) and a capacitor (13). Features.

According to a tenth aspect of the present invention, there is provided the control device according to any one of the first to ninth aspects, wherein the input when the polyphase AC power supply is in a balanced state is provided. The maximum value is predicted by adding a current increase (ΔI) when the polyphase AC power supply (10) is in an unbalanced state to a current (Iin).

A control device (1) according to an eleventh aspect of the present invention is the control device (1) according to the tenth aspect, wherein the unbalanced state is one of the inter-phase voltages of the polyphase AC power supply (10). It is characterized by an unbalanced state when one inter-phase voltage is higher than the reference voltage and another inter-phase voltage is lower than the reference voltage.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a control device 1 according to the present embodiment, and more specifically, a circuit diagram showing a motor 30 for a compressor of an air conditioner and its peripheral circuits. For example, R,
A voltage supplied from a three-phase AC power supply 10 having three phases of S and T is rectified into a DC current having a ripple by a diode bridge 11 having a known configuration. This is filtered by, for example, a choke input type filter, and a DC voltage is supplied 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, three-phase alternating current to the motor 30 to drive the motor 30.

FIG. 1 shows a choke input type filter.
, A capacitor 13 having one end and the other end connected to the negative output terminal (-) of the diode bridge 11, the other end of the capacitor 13, and the positive output terminal (+) of the diode bridge 11; And an inductor 12 interposed therebetween. The negative output terminal of the diode bridge 11 is grounded, for example.

The control circuit 20 comprises, for example, a central processing unit, and controls the operation of the inverter 15. The control circuit 20 has three analog input ports AN0,
AN1 and AN2, and a voltage detection circuit 2
1. The voltage detection value Vm, the current detection value Im, and the peak current, which are the outputs of the current detection circuit 22 and the peak detection circuit 23, are input. When causing the inverter 15 to perform the operation of rotating the motor 30, the input current from the three-phase AC power supply 10 is predicted based on these detected values, and the inverter 15 is controlled so as to be within the allowable range of the breaker 16. Then, the motor which is the load is driven. The peak current input from the peak detection circuit 23 is for the control circuit 20 to recognize the driving capability of the motor 30.

The voltage detection circuit 21 is constituted by, for example, a filter, measures a voltage at a connection point between the inductor 12 and the capacitor 13, and outputs a ripple component of the voltage as a voltage detection value Vm. The current detection circuit 22 is constituted by, for example, an average value circuit or a peak hold circuit, detects a pulse-shaped current flowing between the negative output terminal of the diode bridge 11 and the inverter 15, and determines 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 interposed between the negative input terminal (−) and the voltage drop there.

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

The current detection value Im detected by the current detection circuit 22 has a correlation with the input current input from the three-phase AC current 10 to the diode bridge 11. If the input current is Iin, then Iin = α · Im + β (where α and β are constants). In the balanced state of the three-phase AC power supply 10, the current of each phase (R, S, T) is equal. Therefore, if the current detection 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 current of each phase of R, S and T is not uniform. Therefore, the control circuit 20
Predicts the maximum current of the current of each phase from the ripple component obtained as the voltage detection value Vm. The prediction is based on the assumption that the state has changed from an equilibrium state to an unbalanced state.
This is performed by estimating I from the ripple component and adding ΔI to the input current Iin in the equilibrium state.

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

Assuming that the maximum input current of each phase current in the unbalanced state is Imax, the input current Imax is obtained by adding the current increase ΔI in the unbalanced state to the input current Iin in the balanced state. , Imax = Iin + ΔI = α · Im + a · Vm + β + b.

Each of the parameters α, a, β, which are constants,
+ B is experimentally obtained in advance, and the control circuit 20 performs an arithmetic process by substituting 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-described correction formula. When the three-phase AC power supply 10 is in an unbalanced state, the maximum current Ima of the current flowing through each phase
It becomes possible to predict x.

Assuming that the three-phase AC power supply 10 is in an unbalanced state, the inter-phase voltage of one of the three phases R, S, and T is higher than the reference voltage (for example, 200 V), and the other two inter-phase voltages are different. A first unbalanced state smaller than the reference voltage, wherein one inter-phase voltage is higher than the reference voltage, another one inter-phase voltage is equal to the reference voltage, and the other one inter-phase voltage is lower than the reference voltage. There are three aspects of two unbalanced states and a third unbalanced state in which two inter-phase voltages are higher than the reference voltage and another one inter-phase voltage is lower than the reference voltage.

Here, the unbalance rate is 2% (for example, when the reference voltage is 2%).
00V, and the inter-phase voltage has a variation of about ± 4 V with respect to the reference voltage). When the experiment is performed on the above three aspects, the respective parameters of the correction equation in the first unbalanced state are obtained. If so, the maximum current Imax can be predicted using the correction formula even in other unbalanced states. In other words, of the three aspects, the amount of correction for estimating the maximum current Imax is greatest in the first unbalanced state, and therefore the maximum current Imax is estimated using the correction formula in the other unbalanced state. However, the predicted value does not actually fall below the value of the current flowing from the three-phase AC power supply 10 to each phase.

Therefore, of the three aspects, each parameter of the above-mentioned correction formula is changed for the first unbalanced state when one inter-phase voltage is higher than the reference voltage and the other two inter-phase voltages are lower than the reference voltage. The maximum current I
By controlling max within the allowable range of the breaker 16, the inverter 15 can be controlled to drive the motor 30 without operating the breaker 16 even in 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. In the graph of FIG. 2, the horizontal axis is actually measured by an ammeter inserted between the three-phase AC power supply 10 and the diode bridge 11. This figure shows the input maximum current, which is the maximum current in the R, S, and T phases, when the output frequency is increased while reproducing the state and driving the motor 30 under the same conditions as the equilibrium state. The vertical axis indicates the current detection value Im input to the control circuit 20 and the current value of the maximum current Imax derived as a result of the arithmetic processing based on the correction formula in the control circuit 20.

As shown in FIG. 2, for example, the output frequency 104H
When the motor 30 is driven at z, the detected current value Im input to the control circuit 20 is 16.1 A even though the maximum input current actually input from the three-phase AC power supply 10 is 21.1 A. . Also, when driven at an output frequency of 128 Hz, the detected current value Im input to the control circuit 20 is 19.000, although 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.degree., 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
It 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 for operating the breaker 16, the output frequency is 21
When the frequency reaches 6 Hz, the current detection value I detected by the control circuit 20
Despite the fact that m is less than 30A, the breaker 16 is activated and the whole apparatus stops.

On the other hand, in the present embodiment, 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-described correction formula. As shown in the graph, it is possible to predict the maximum current that substantially matches the actual input maximum current. For this reason, 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 is determined. Control signal can be supplied to the inverter 15.

Therefore, if the current value for operating the breaker 16 is set in the control circuit 20 in advance, the control circuit 20 outputs the current value from the three-phase AC power supply 10 based on the detected voltage value Vm and the detected current value Im. Since the maximum input current is predicted and the motor 30 is driven by controlling the inverter 15 so that the predicted maximum current falls within the allowable range, the circuit breaker 16 is not operated even in an unbalanced state, and Even in such a situation, the motor 30 can be driven by effectively using the power of the power source within a range permitted by the breaker 16. In other words, it is possible to perform drive control to reduce the operation capability of the motor 30 before the breaker 16 operates.

In the above-mentioned correction formula, the maximum current I is obtained by using the voltage detection value Vm inputted to the control circuit 20 as it is.
Although the method of estimating max has been described, even when the three-phase AC power supply 10 is in an equilibrium state, a ripple component of about 5 or 6 V (referred to as an ideal ripple voltage Vr) is detected as the voltage detection value Vm. Is done. Therefore, in the unbalanced state, the correction formula is a correction formula for appropriately predicting the maximum current. However, when the same processing is performed in the balanced state, the ripple component in the balanced state is not 0. 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 following equation is obtained from Vm ′ = Vm−Vr.
= 5-6V) is obtained, and each parameter is obtained using the ripple voltage Vr instead of the voltage detection value Vm. Also, when the control circuit 20 performs actual control, Based on the above equation, the voltage detection circuit 21
The maximum current is predicted by performing an arithmetic process using the ripple voltage Vm ′ obtained by subtracting the ideal ripple voltage Vr from the input voltage detection value Vm instead of Vm in the above-described correction formula, and the motor drive is controlled. Is preferable. With this 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, the control device 1 of the present embodiment is configured such that the AC current from the three-phase AC power supply 10 is rectified by the diode bridge 11, and after the rectification is subjected to a filtering process to detect a ripple voltage. . Then, the filtering process is performed by a filter unit realized by the inductor 12 and the capacitor 13. When the capacitor 13 is used for a long time, the capacitor 13 tends to change with time and the capacitance tends to decrease. Therefore, each parameter applied to the above-described correction formula becomes a parameter for predicting an appropriate maximum current at the time of manufacturing the control device 1, but with a decrease in the capacitance of the capacitor 13 due to subsequent use. May not be optimal parameters.

However, since the maximum current is predicted using the above-described correction formula, even if the capacitor 13 is reduced in capacity due to aging and each parameter is no longer optimal, the input from the three-phase AC power supply 10 is actually performed. Since the maximum current value to be predicted is larger than the current value to be predicted, the breaker does not need to be activated, and there is no problem.

In the above description, whether the input frequency from the three-phase AC power supply 10 is 50 Hz or 60 Hz is not particularly mentioned, but if these are different, they are detected as the voltage detection value Vm. Since the ripple components show different tendencies, each parameter (constants a and b) of the above-mentioned correction formula also becomes different.

Therefore, the control circuit 20 determines the type of the three-phase AC power supply 10, that is, the input frequency is 50 Hz or 60 Hz.
It is desirable to configure so as to have a function of identifying which one of the above, and to realize the maximum current Imax based on the correction formula by selecting an optimal parameter based on the identification result. Specifically, when the control device 1 is installed, a jumper wire (not shown) in the control circuit 20 is connected or disconnected, a dip switch is switched, or the like. Can be recognized. By realizing such a configuration, the maximum current Imax can always be appropriately predicted according to the environment in which the control device 1 is installed, and the performance of the motor 30 can be maximized without operating the breaker 16. It is possible to drive the operation so that

Further, even when the driving capability of the compressor is different, each parameter is different, so that the control circuit 20 recognizes the driving capability of the compressor based on the peak current from the peak detecting circuit 23. If the maximum current Imax is predicted by selecting an optimal parameter according to the recognition result, 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 the present embodiment, the maximum value of the input current from the three-phase AC power
The prediction is made based on the rectified ripple component. On the other hand, each phase R, S,
Even if it is configured to directly detect all the current flowing through T, the operation capability of the motor 30 can be reduced before the breaker operates, but in this case, the number of required sensors increases and the There is a possibility that the size and cost will increase.

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, it is possible to reduce the size and cost of the control device 1 and thereby reduce the air flow. It also makes it possible to reduce the size and cost of the entire harmony machine.

The embodiments of the present invention have been described above, but 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. However, the present invention is not limited to this, and it is sufficient if the power supply is a polyphase AC power supply that may cause an unbalanced state. .

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

[0048]

As described above, 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 falls within the allowable current range. In order to drive the load, for example, the driving state of the load can be reduced before exceeding the allowable current range. For this reason, it is possible to drive the load without operating the breaker even under a situation where the power is unbalanced in the polyphase AC power supply, and under such a situation, the power supply power is effectively used.

According to the fourth aspect of the present invention, 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. Also, the load drive can be performed without operating the breaker and effectively using the power of the power supply.

According to the fifth aspect of the present invention, since the arithmetic processing is performed by using the parameters corresponding to the type of the polyphase AC power supply, it is always appropriate for the installation environment of the control device. The maximum value of the input current can be predicted.

According to the sixth aspect of the present invention, since the arithmetic processing is performed by using the parameter corresponding to the driving capability of the polyphase load, the control device is adapted to the load to which the control device is applied. The maximum value of the input current can always be appropriately predicted.

Further, according to the invention of claim 7, the maximum current which is a factor for operating the breaker can be appropriately predicted, and the load can be driven without operating the breaker.

According to the ninth aspect of the present invention, the load can be driven without operating the breaker even when the capacitor changes over time.

According to the tenth aspect of the present invention, the amount of current increase when the polyphase AC power supply is in an unbalanced state is added to the input current when the polyphase AC power supply is in a balanced state. Therefore, the maximum current can be predicted without directly measuring the input current.

According to the eleventh aspect of the present invention, among the inter-phase voltages of the polyphase AC power supply, when one inter-phase voltage is higher than the reference voltage and another inter-phase voltage is lower than the reference voltage. Since the configuration is such that the amount of current increase 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 another unbalanced state.

[Brief description of the drawings]

FIG. 1 is a diagram showing a control device.

FIG. 2 is a diagram showing a result of an experiment for estimating a maximum current.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 controller 10 three-phase AC power supply 11 diode bridge 12 inductor 13 capacitor 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

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G066 GA02 GB02 GC02 5H007 BB06 CA01 CC01 DA04 DA05 DA06 DB02 DB12 DC02 DC05

Claims (11)

[Claims] 1. A maximum value of an input current from a polyphase AC power supply is predicted based on a ripple component (Vm) obtained by rectifying an output of the polyphase AC power supply, and the maximum value is an allowable current. A control device (1) for driving a polyphase load (30) using the polyphase AC power supply so as to fall within the range of (1). 2. The control device (1) according to claim 1, wherein control means (20) predicts the maximum value,
A control device, wherein a control signal is supplied to the drive circuit (15) for driving the polyphase load (30) such that the maximum value is within a range of an allowable current. 3. The control device (1) according to claim 2, wherein the control unit (20) performs a predetermined arithmetic process on the ripple component (Vm) to estimate the maximum value. A control device characterized by performing. 4. The control device (1) according to claim 3, wherein the control means (20) balances the polyphase AC power when performing the arithmetic processing based on the ripple component (Vm). A control device, wherein the arithmetic processing is performed by subtracting an ideal ripple voltage in the case of a state from a ripple voltage (Vm). 5. A 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 polyphase AC power supply (10), and performs the arithmetic processing using a parameter corresponding to the type. 6. The control device (1) according to claim 3 or 4.
The control device according to claim 1, wherein the control means (20) has a function of recognizing a driving capability of the multi-phase load (30), and performs the arithmetic processing using a parameter corresponding to the driving capability. . 7. The control device (1) according to claim 1, wherein the maximum value is a maximum current among currents flowing through each phase of the polyphase AC power supply (30). A control device characterized by the above-mentioned. 8. The control device (1) according to claim 1, wherein the ripple component (Vm) is detected by performing a filtering process after the rectification. 9. The control device (1) according to claim 8, wherein the filtering is performed by an inductor (12) and a capacitor (1).
A control device characterized by being realized by 3). 10. The control device (1) according to any one of claims 1 to 9, wherein the input current (Iin) when the polyphase AC power supply (10) is in an equilibrium state is set to the polyphase AC power supply (10). 10) The control device, wherein the maximum value is predicted by adding a current increase (ΔI) when the device is in an unbalanced state. 11. The controller (1) according to claim 10, wherein in the unbalanced state, one of the inter-phase voltages of the polyphase AC power supply (10) is higher than a reference voltage, A control device characterized by being in an unbalanced state when another inter-phase voltage is smaller than a reference voltage.