JPH09271197A - Control equipment of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify structure and improve incorporation work, by making it possible to heat refrigerator oil without installing a crank case heater. SOLUTION: This control equipment converts electric power supplied from a power source PS to specified controlled three-phase AC power, outputs it to an induction motor CM, pulse-width-modulates the supply voltage to the induction motor CM, and controls a power converter circuit 20 in such a manner that the induction motor CM is subjected to variable speed control. On the other hand, when a preheating signal is receive during halt of the induction motor CM, the control equipment outputs one phase supply voltage out of the supply voltage to the induction motor CM, as a pulse-width-modulated voltage signal, to the induction motor CM, and outputs the other two-phase supply voltage, as a continuous voltage signal of the same phase square wave AC which is not pulse-width-modulated and held at a specified voltage, to the induction motor CM. As a result, heat is generated without rotating the induction motor CM.

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 an electric motor, and more particularly to a measure for controlling a supply voltage of the electric motor.

[0002]

2. Description of the Related Art Conventionally, air conditioner compressors have been
Refrigeration and Air Conditioning Handbook (4th edition, published by Japan Refrigeration Association)
As disclosed in pages 375 and 376 of the basic edition of the above, some cases have a crankcase heater attached. That is, the crankcase of the compressor is filled with refrigerating machine oil, but the refrigerant may be mixed in the refrigerating machine oil when the outside air temperature is low, such as during winter stoppage.

If the refrigerant is started while being mixed with the refrigerating machine oil, the refrigerant in the refrigerating machine oil boils, so-called oil forming occurs, and the compressor may stop without increasing the hydraulic pressure. Therefore, while the compressor is stopped, the crankcase heater is energized to heat the refrigerating machine oil so that the refrigerant is not mixed.

[0004]

However, in the above-mentioned compressor, since the crankcase heater is used, there is a problem that the number of parts increases and the structure becomes complicated.

Further, since it is necessary to attach the crankcase heater, there is a problem that the workability of assembling the compressor is poor.

The present invention has been made in view of the above problems, and is capable of heating refrigerating machine oil and the like without providing a crankcase heater so that the structure can be simplified and the assembling workability can be improved. The purpose is to do.

[0007]

[Means for Solving the Problems]

-Summary of the Invention-The present invention converts the electric power supplied from the power supply (PS) into a predetermined controlled three-phase AC power and outputs the electric power to the electric motor (CM), and the supply voltage of the electric motor (CM) is pulsed. Power conversion circuit (20) to control the motor (CM) at variable speed by width modulation
On the other hand, when receiving a preheat signal while the electric motor (CM) is stopped, it outputs to the electric motor (CM) as a modulation voltage signal obtained by pulse-width-modulating the supply voltage of one phase of the supply voltage of the electric motor (CM). The other two-phase supply voltage is output to the electric motor (CM) as a continuous voltage signal of the same phase square wave AC that is held at a predetermined voltage value that is not pulse width modulated, and heat is generated without rotating the electric motor (CM). .

-Specific Items of the Invention-Specifically, as shown in FIG. 1, the means taken by the invention according to claim 1 first comprises a power source (PS) and an electric motor (CM). Then, the electric power supplied from the power source (PS) is converted into a predetermined controlled three-phase AC power, and the electric motor (CM) is converted.
Power conversion circuit (20) for outputting to the power conversion circuit (2
0) is provided with a drive circuit (31) for outputting a drive signal. Further, a control signal for controlling the supply frequency of the electric motor (CM), which is a control signal for pulse-width modulating the supply voltage of the electric motor (CM) to control the electric motor (CM) at a variable speed, is sent to the drive circuit (31). A speed control means (41) for outputting is provided. In addition, when the preheat signal is received while the electric motor (CM) is stopped, at the same time the power conversion circuit (20) outputs a modulation voltage signal obtained by pulse-width-modulating the supply voltage of one phase of the supply voltage of the electric motor (CM). , A preheat control signal is output to the drive circuit (31) so that the power conversion circuit (20) outputs it as a continuous voltage signal that holds the supply voltage of the other two phases at a predetermined voltage value that is not pulse width modulated, and the motor (CM (4) is provided with heat generation control means (43).

The means taken by the invention according to claim 2 comprises a power source (PS) and an electric motor (CM). Then, a power conversion circuit (20) for converting the power supplied from the power supply (PS) into a predetermined controlled three-phase AC power and outputting it to the electric motor (CM), and driving the power conversion circuit (20). A drive circuit (31) for outputting a signal is provided. Furthermore,
Speed control means for controlling the supply frequency of the electric motor (CM) and for outputting a control signal for pulse-width modulating the supply voltage of the electric motor (CM) to control the electric motor (CM) at a variable speed to the power conversion circuit (20). (41) is provided. In addition, when the stop signal of the electric motor (CM) is received, the speed control means (4
Instead of 1), the power conversion circuit (20) outputs the modulation voltage signal obtained by pulse-width-modulating the supply voltage of one phase of the supply voltage of the motor (CM), and at the same time does not pulse-modulate the supply voltage of the other two phases A discharge control means (44) for discharging a charge of the power conversion circuit (20) by outputting a discharge control signal to the drive circuit (31) so that the power conversion circuit (20) outputs it as a continuous voltage signal held at a predetermined voltage value. ) Is provided.

Further, the means taken by the invention of claim 3 is that in the invention of claim 1 or 2, the two-phase supply voltages which are continuous voltage signals are square wave alternating currents of the same phase. There is.

Further, the means taken by the invention according to claim 4 is that in the invention according to claim 1 or 2, the electric motor is a motor of a compressor provided in the air conditioner.

-Operation- According to the above-mentioned invention specifying matter, in the invention of claim 1,
First, when the power source (PS) is turned on and the operation command is output, the speed control means (41) outputs a control signal and the drive circuit (31) outputs the drive signal to the power conversion circuit (20). The power converter circuit (20) applies a predetermined supply voltage pulse-width modulated to the electric motor (CM).

On the other hand, when the heat generation control means (43) receives a preheat signal while the electric motor (CM) is stopped, for example, in the invention described in claim 4, the power source (PS) is turned on for the first time. When the air conditioning operation is started or the compressor is stopped for 15 minutes or more and the discharge pipe temperature T2 of the compressor becomes 7 ° C. or less, the preheat signal Is output. That is, when the outside air temperature is low, the refrigerant may be mixed in the refrigerating machine oil of the compressor.
3) outputs a preheat control signal to the drive circuit (31).

The drive circuit (31) receives the preheat control signal and the power conversion circuit (20) drives to output a predetermined supply voltage. For example, in the invention according to claim 3, the power conversion circuit (20). The V-phase supply voltage is output to the motor (CM) as a pulse-width-modulated modulation voltage, while the U-phase supply voltage and the W-phase supply voltage are square wave corresponding to the cycle of the supply frequency. The AC voltage is output to the electric motor (CM) as a continuous voltage of a predetermined voltage that is not pulse width modulated. As a result, the electric motor (CM) does not rotate,
The electric motor (CM) itself generates heat and heats the refrigerating machine oil.

Further, in the invention according to claim 2, when the rotation of the electric motor (CM) is stopped, the discharge control means (44) instead of the speed control means (41) outputs a discharge control signal to the drive circuit (3).
Output to 1). The drive circuit (31) receives the discharge control signal, the power conversion circuit (20) drives the power conversion circuit (20) to output a predetermined supply voltage, and the V phase output by the power conversion circuit (20) is output in the same manner as the heating control means. The supply voltage is output to the motor (CM) as a pulse-width modulated voltage, while the U-phase supply voltage and the W-phase supply voltage are the corresponding square wave alternating currents whose period is the supply frequency, and It is output to the electric motor (CM) as a continuous voltage of a predetermined voltage that is not width-modulated.

As a result, the electric charge accumulated in the power conversion circuit (20) is discharged through the electric motor (CM). The discharge control signal of the discharge control means (44) is output, for example, for 55 seconds after the electric motor (CM) is stopped to perform the discharge operation.

[0017]

According to the first aspect of the invention, therefore, only one phase of the three-phase AC supply voltage of the electric motor (CM) is a pulse width modulated voltage, and the other two phase supply voltages are used. Since the electric motor (CM) is made to generate heat as a continuous voltage that is not pulse width modulated, the electric motor (CM) itself also serves as a heater, so that the conventional crankcase heater can be omitted.

As a result, the number of parts can be reduced, so that the structure can be simplified and the workability of assembling the compressor and the like can be improved.

According to the second aspect of the present invention, when the electric motor (CM) is stopped, only one phase of the three-phase AC supply voltage is pulse-width modulated, and the other two phase supply voltages are used. Is supplied to the electric motor (CM) as a continuous voltage that is not pulse width modulated, it is possible to reliably discharge the electric charge accumulated in the smoothing capacitor (2C) of the power conversion circuit (20) via the electric motor (CM). Because the power conversion circuit (2
It is possible to reduce the capacity of the discharge resistor (2R) in 0).

According to the third aspect of the present invention, since the two-phase supply voltages are square-wave alternating currents of the same phase that are not pulse-width modulated, rotation of the electric motor (CM) is reliably prevented and heat generation operation and A discharge operation can be performed.

Further, according to the invention of claim 4, in the case of the compressor of the air conditioner, it is possible to reliably prevent the refrigerant from being mixed in the refrigerating machine oil, so that the compressor is smoothly started. You can

[0022]

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

As shown in FIG. 2, (10) is an induction motor (C) of a compressor provided in an outdoor unit of an air conditioner.
M), comprising a power conversion circuit (20) and a power control circuit (30), and supplying control power from a power supply (PS) to the induction motor (CM) via the power conversion circuit (20). doing.

The power conversion circuit (20) converts the three-phase AC power supplied from the power source (PS) into controlled three-phase AC power, and includes a rectifying circuit (21) and a smoothing circuit (2).
2) and an inverter circuit (23). And
The rectifier circuit (21) includes six diodes (d1, d1,
…) And a power supply (P
A diode module connected to S) that performs full-wave rectification on AC from the power supply (PS).

The smoothing circuit (22) smoothes the direct current that has been full-wave rectified by the rectifying circuit (21). The smoothing circuit (22) is provided with a reactor (2L) and has a smoothing capacitor (2C). 2a) and a resistor circuit (2b) having a discharge resistor (2R) are connected to the power supply line (2P, 2
N). The smoothing circuit (22) has a DC section current, that is, an induction motor (C
A current transformer (CT) that is a current detector that detects a motor current that is the current of M) is provided in the power supply line (2N).

The inverter circuit (23) is a transistor including six power transistors (Tr, Tr, ...).
A smoothing circuit (22) is a transistor module that converts a smoothed direct current into an alternating current, and is connected to an induction motor (CM) to supply three-phase AC control power to the induction motor (CM). I have. A free wheeling diode (d2, d2, ...) Is connected between the emitter and collector of the power transistor (Tr, Tr, ...), and the power transistor (Tr, Tr ,. ON / OFF by the drive signal of).

The electric power control circuit (30) is provided with a drive circuit (31) and a CPU (40) while a current signal is input from a current transformer (CT). The drive circuit (31) controls the power transistors (Tr, Tr,...) So that the power transistors (Tr, Tr,...) Perform PWM modulation (pulse width modulation) on the DC section voltage smoothed by the smoothing circuit (22).
The drive signal is output to. An air conditioning load signal such as an indoor temperature is input to the CPU (40).
Speed control means (41) and optimum control means (42) are provided.

The speed control means (41) receives an air conditioning load signal such as the room temperature, and derives the supply frequency of the induction motor (CM) which is the operating frequency of the compressor in response to the air conditioning load signal. Then, the control signal is output to the drive circuit (31) so as to achieve this supply frequency.

That is, the speed control means (41) controls the drive of the inverter circuit (23) so that the supply frequency and the supply voltage of the induction motor (CM) change based on the preset reference voltage frequency characteristic. A control signal for controlling the supply frequency of the induction motor (CM) to control the induction motor (CM) at a variable speed is output to the drive circuit (31). Then, the drive circuit (31) outputs the drive signal to the inverter circuit (23) of the power conversion circuit (20) based on the control signal.

The optimum control means (42) drives an adjustment signal for adjusting the supply voltage of the induction motor (CM) so that the supply voltage of the induction motor (CM) is slightly changed by a predetermined change amount so that the motor current is minimized. Outputting to the circuit (31). Then, the drive circuit (31) outputs the drive signal to the inverter circuit (23) of the power conversion circuit (20) based on the adjustment signal.

The CPU (40) is provided with heat generation control means (43) and discharge control means (44) as a feature of the present invention. The heat generation control means (43) is an induction motor (C
Induction motor (CM) when the preheat signal is received while M) is stopped.
Of the supply voltage of 1 phase, the power conversion circuit (20) outputs as a modulation voltage signal obtained by pulse-width-modulating the supply voltage of one phase, and at the same time, the continuous voltage signal that holds the supply voltage of the other 2-phases at a predetermined voltage value that does not perform pulse width modulation. As a power conversion circuit (20), a preheating control signal is output to the drive circuit (31) to heat the induction motor (CM) without rotating it.

When the discharge control means (44) receives the stop signal for the induction motor (CM), the speed control means (41).
Instead of the heat generation control means (43), the supply voltage of one phase of the supply voltage of the induction motor (CM) is used as the modulation voltage signal, and the supply voltages of the other two phases are used as continuous voltage signals that are not pulse width modulated. Discharges the smoothing capacitor (2C) in the power conversion circuit (20) without rotating the induction motor (CM) by outputting the discharge control signal to the drive circuit (31) so that the power conversion circuit (20) outputs it. Let

Specifically, as shown in FIG. 3, the V-phase supply voltage Sv is output from the power conversion circuit (20) to the induction motor (CM) as a pulse-width modulated modulation voltage, while U
The supply voltage Su of the phase and the supply voltage Sw of the W phase are corresponding square wave alternating currents having a cycle of the supply frequency, and are a continuous voltage of a predetermined voltage which is not pulse-width modulated, and are supplied from the power conversion circuit (20) by the induction motor. It is output to (CM).

Further, the U-phase supply voltage Su and the W-phase supply voltage Sw are configured as an in-phase square-wave alternating current so that no current flows between the U-phase and the W-phase. (CM) does not rotate.

Further, although not shown, the preheat signal receives a discharge pipe temperature signal from a temperature sensor for detecting the discharge pipe temperature T2 of the compressor, and is output or stopped under the following conditions. There is.

The preheat signal is either from the time when the power source (PS) is turned on to the time when the first air conditioning operation is started, or after the compressor is stopped and 15 minutes or more have passed. In this state, when the discharge pipe temperature T2 of the compressor becomes 7 ° C. or lower, the output is made.

As for the preheat signal, either a temperature control operation start command (thermo-on command) is output, or the discharge pipe temperature T2 of the compressor is higher than 9.5 ° C., whichever condition is satisfied. Then, the output is stopped.

—Control Operation of Induction Motor (CM) — Next, the control operation of the above-described induction motor (CM) will be described.

First, in the state where the power supply (PS) is turned on and the switching circuit (11) is turned on, when an operation command such as a cooling operation is output from a remote controller (not shown), the CPU (40) receives this operation command. Then, the speed control means (41) outputs a control signal. The drive circuit (31) receives this control signal, outputs the drive signal to the inverter circuit (23), and the power transistors (Tr, Tr, ...) Are turned on / off.

On the other hand, the three-phase AC power from the power source (PS) is full-wave rectified by the rectifier circuit (21) and converted into direct current, smoothed by the smoothing circuit (22), and then the inverter circuit ( 23) is output. And six power transistors (Tr, Tr,...) Of the inverter circuit (23).
Converts a direct current into an alternating current and supplies a predetermined supply voltage to an induction motor (CM) by pulse width modulation.

An air conditioning load signal such as room temperature is input to the CPU (40), and the speed control means (41)
The supply frequency of the induction motor (CM), which is the operating frequency of the compressor, is derived in response to the air conditioning load signal, and a control signal is output to the drive circuit (31) so as to reach the supply frequency. That is, the speed control means (41) controls the drive of the inverter circuit (23) so that the supply frequency and the supply voltage of the induction motor (CM) change based on the preset reference voltage frequency characteristic. And the drive circuit (31) outputs a drive signal to the inverter circuit (23) based on the control signal. As a result, the induction motor (CM)
Will rotate in response to the air conditioning load.

When the induction motor (CM) is rotating, the optimum control means (42) slightly changes the supply voltage of the induction motor (CM) by a predetermined fluctuation amount so that the motor current is minimized. The adjustment signal is output to the drive circuit (31). Then, the drive circuit (31) outputs a drive signal to the inverter circuit (23) based on the adjustment signal so that the induction motor (CM) rotates at the most efficient minimum current value.

On the other hand, when the air conditioning operation is stopped and the rotation of the induction motor (CM) is stopped, for example, when an operation stop command is output from the remote controller, this operation stop command is sent to the CPU.
When the induction motor (CM) stops rotating, the discharge control means (44) instead of the speed control means (41) receives the discharge control signal from the drive circuit (31). ) Is output. The drive circuit (31) receives this discharge control signal, and the six power transistors (Tr, T) of the inverter circuit (23) are received.
ON / OFF control of r, ...). Among the supply voltages output to the induction motor (CM) by the inverter circuit (23), as shown in FIG. 3, the V-phase supply voltage Sv is supplied to the induction motor (CM) as a pulse width modulated voltage. While being output, the U-phase supply voltage Su and the W-phase supply voltage Sw
Is a corresponding square wave alternating current having a cycle of the supply frequency, and is output to the induction motor (CM) as a continuous voltage of a predetermined voltage that is not pulse width modulated.

As a result, the electric charge accumulated in the smoothing capacitor (2C) of the capacitor circuit (2a) in the smoothing circuit (22) is discharged through the resistance circuit (2b), and at the same time, the induction motor (CM) rotates. Without this, the electric charge accumulated in the smoothing capacitor (2C) is discharged through the induction motor (CM). The discharge control signal of the discharge control means (44) is output, for example, for 55 seconds after the induction motor (CM) is stopped to perform the discharge operation.

On the other hand, the preheat signal may be received by the CPU (40) while the induction motor (CM) is stopped. Specifically, either from the time when the power (PS) is turned on to the time when the first air conditioning operation is started, or after the compressor is stopped and 15 minutes or more have passed, and When the discharge pipe temperature T2 of the compressor becomes 7 ° C. or lower, a preheat signal is output. That is, when the outside air temperature is low, the refrigerant may be mixed in the refrigerating machine oil of the compressor.
Upon receiving the preheat signal, the heat generation control means (43) outputs a preheat control signal to the drive circuit (31). The drive circuit (31) receives the discharge control signal to control ON / OFF of the six power transistors (Tr, Tr, ...) Of the inverter circuit (23).

The supply voltage output from the inverter circuit (23) to the induction motor (CM) is the same as the discharge control means (44), as shown in FIG.
v is an induction motor (C
On the other hand, the U-phase supply voltage Su and the W-phase supply voltage Sw, which are output to M), are the corresponding square wave alternating currents whose period is the supply frequency, and are continuous voltages of a predetermined voltage that are not pulse width modulated. Output to the induction motor (CM).

As a result, the induction motor (CM) itself generates heat and heats the refrigerating machine oil without rotating the induction motor (CM). Output of the preheat signal is stopped when a temperature control operation start command (thermo-on command) is output, or the discharge pipe temperature T2 of the compressor is higher than 9.5 ° C., or either condition is satisfied. Therefore, the preheating control signal of the heat generation control means (43) stops and the induction motor (C
The heating operation of M) will stop.

-Effects of this Embodiment- As described above, according to this embodiment, an induction motor (CM) is used.
In the three-phase AC supply voltage, only one phase is used as a modulation voltage that is pulse-width modulated, and the other two-phase supply voltages are used as continuous voltages that are not pulse-width modulated to heat the induction motor (CM). Since the electric motor (CM) itself also serves as a heater, the conventional crankcase heater can be omitted.

As a result, the number of parts can be reduced, so that the structure can be simplified and the workability of assembling the compressor and the like can be improved.

Particularly, in the case of the compressor of the air conditioner, it is possible to reliably prevent the refrigerant from being mixed in the refrigerating machine oil, so that the compressor can be smoothly started.

When the induction motor (CM) is stopped,
Of the three-phase AC supply voltage, only one phase is used as the modulation voltage that is pulse-width modulated, and the other two-phase supply voltages are supplied as continuous voltage that is not pulse-width modulated to the induction motor (CM). Smoothing capacitor (2C) of circuit (20)
Since the electric charge accumulated in the capacitor can be surely discharged through the induction motor (CM), the capacity of the discharge resistor (2R) of the resistance circuit (2b) can be reduced.

Further, since the two-phase supply voltages are square-wave alternating currents of the same phase that are not pulse width modulated, the induction motor (CM)
It is possible to reliably prevent the rotation of the above and perform the heat generation operation and the discharge operation.

[0053]

Other Embodiments In the present embodiment, the continuous voltage not pulse-width-modulating the two-phase supply voltage is a square wave alternating current, but in the invention of claims 1 and 2, the two-phase The supply voltage may be a DC voltage having the same potential.

In addition, although the induction motor (CM) of the compressor of the air conditioner has been described in the present embodiment, the invention described in claims 1 to 3 applies to various induction motors (CM). However, the present invention is not limited to induction motors (CMs).

Further, although the inverter circuit (23) in this embodiment uses six power transistors (Tr, Tr, ...), in the present invention, six IGBTs (Insulated Gate) are used.
Bipolar Transistor) may be used.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a control circuit diagram of the induction motor.

FIG. 3 is a waveform diagram showing a supply voltage waveform of the induction motor.

[Explanation of symbols]

 20 Power conversion circuit 21 Rectifier circuit 22 Smoothing circuit 23 Inverter circuit 30 Power control circuit 31 Drive circuit 40 CPU 41 Speed control means 43 Heating control means 44 Discharge control means PS Power source CM Induction motor

Claims (4)

[Claims] 1. A power provided with a power supply (PS) and an electric motor (CM), while converting the electric power supplied from the power supply (PS) into a predetermined controlled three-phase AC power and outputting the electric power to the electric motor (CM). A converter circuit (20), a drive circuit (31) for outputting a drive signal to the power converter circuit (20), and a control signal for controlling the supply frequency of the electric motor (CM), which is supplied by the electric motor (CM). Speed control means (41) for outputting a control signal for controlling the variable speed of the electric motor (CM) to the drive circuit (31) by pulse-width modulating the voltage, and receiving a preheat signal while the electric motor (CM) is stopped, Of the supply voltage of the motor (CM), the power conversion circuit (20) outputs a one-phase supply voltage as a pulse width-modulated modulation voltage signal, and at the same time holds the other two-phase supply voltages at a predetermined voltage value that is not pulse width modulated. The power converter circuit (20) outputs it as a continuous voltage signal Preheat control signal to drive circuit (31)
To heat the motor (CM)
3) A control device for an electric motor comprising: 2. A power which comprises a power supply (PS) and an electric motor (CM), and which converts the electric power supplied from the power supply (PS) into a predetermined controlled three-phase AC power and outputs the electric power to the electric motor (CM). A converter circuit (20), a drive circuit (31) that outputs a drive signal to the power converter circuit (20), and a supply frequency of the electric motor (CM) is controlled, and a supply voltage of the electric motor (CM) is pulse width. A speed control means (41) that modulates and outputs a control signal for variable speed control of the electric motor (CM) to the power conversion circuit (20), and a speed control means (41) when the stop signal of the electric motor (CM) is received. Instead of the output voltage of the motor (CM), the power conversion circuit (20) outputs as a modulation voltage signal obtained by pulse-width-modulating the supply voltage of one phase, and at the same time, a predetermined voltage that does not pulse-modulate the supply voltage of the other two phases. The power conversion circuit (20) outputs a continuous voltage signal that holds the value Control unit for an electric motor, characterized in that the discharge control signal so as to force output to the drive circuit (31) and a charge and discharge control means for discharging (44) of the power conversion circuit (20). 3. The motor control device according to claim 1, wherein the two-phase supply voltages, which are continuous voltage signals, are in-phase square-wave alternating current. 4. The electric motor control device according to claim 1, wherein the electric motor is a compressor motor provided in an air conditioner.