JPH10295095A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid switching shocks, such as the sudden change of a motor speed at the time of switching between PWM control and PAM control, stabilize the speed control at the time of the switching, and make a motor operate at a maximum speed consistently. SOLUTION: A controller has two speed control systems, i.e., PWM control 803 which controls the speed of a motor, based on the conduction rate of an inverter and PAM control 801 which controls the speed of the motor in accordance with a DC voltage outputted by a chopper circuit. A speed control means 80, consisting of a means 802 which switches the two speed control systems with each other in accordance with the control state, is provided. The speed of the motor is used as the switching condition between the two speed control systems and, furthermore, a switching transition region is provided. When the speed control system is switched from one to the other, the conduction rate of the inverter and the DC voltage are gradually changed in accordance with predetermined rates in the switching transition region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a motor control device,
In particular, the present invention relates to a motor control device that controls the speed of a motor by switching between PWM / PAM control.

[0002]

2. Description of the Related Art Conventionally, a rectifier circuit for rectifying an AC power supply and converting it to a DC power supply has been used as a motor control device for controlling the speed of a motor by combining a power supply circuit for controlling a DC voltage and a motor drive circuit. JP-A-61-10968, JP-A-59-198897 and JP-A-59-198897.
There is a method described in Japanese Patent Application No. 181973. These systems use PWM (Puls) using a motor drive circuit at low speed.
e Width Modulation) control the speed of the motor, and at high speeds, use a DC voltage control of the power supply circuit to control the speed of the motor.
The motor speed is controlled by Amplitude Modulation control. Further, when the control is switched from the PWM control to the PAM control, there is a method of changing the flow rate of the motor drive circuit to 100%, a method of maintaining the flow rate at the time of the switching, or a method of setting a fixed flow rate pattern. Such PWM control and P
The switching of the AM control is performed by a set value of a motor speed, a speed command (frequency or frequency command), or a value related to the motor speed, such as a voltage applied to the motor. Also, PW
A method of suddenly changing the DC voltage at the time of switching between the M control and the PAM control and changing the chopper pattern system of the motor drive circuit are disclosed in Japanese Patent Application Laid-Open Nos. 58-86871 and 58-8871.
No. 12577.

[0003]

In the above conventional methods, the switching point (set value) between the PWM control and the PAM control is predetermined in each case. Shock such as sudden change in speed occurs. Further, in a system in which the state of the flow rate or the DC voltage before the switching is maintained after the switching, efficient control at the operating point cannot always be performed. Further, depending on the load condition, the switching condition value may not reach the set value, so that the control method is not changed, and it is expected that the speed control of the motor itself becomes impossible. In particular, general equipment such as an inverter air conditioner has a wide load range and a large fluctuation range of power supply. Therefore, it is difficult to apply the above-described conventional method to these equipment.

SUMMARY OF THE INVENTION An object of the present invention is to prevent a switching shock such as a sudden change in motor speed when switching between PWM control and PAM control, and to stabilize the speed control at the time of switching, so that a motor capable of always operating at maximum efficiency. It is to provide a control device.

[0005]

In order to solve the above problems, PWM control for controlling the speed of the motor based on the duty factor of the inverter and speed control of the motor based on the DC voltage output from the chopper circuit are performed. It has two speed control systems of PAM control, and has speed control means for switching between the two speed control systems depending on the control state, and is provided with a motor speed or a command speed or a motor applied voltage or a motor speed including a duty ratio of an inverter. At least one of the values that change in relation to each other is used as a switching condition for the two speed control systems, and a switching transition region is provided. When the two speed control systems are switched, the duty ratio of the inverter and the DC current are switched in the switching transition region. The voltage is changed according to a preset rate. Further, at least two switching conditions for the two speed control systems are set.
Two different values are set, and a switching transition area is set between the values to provide a hysteresis characteristic. Further, when the actual speed of the motor reaches the commanded speed when the two speed control systems are switched, the duty ratio of the inverter or the DC voltage is stopped from changing in accordance with the preset rate, and the flow of the inverter at the time of the stop is stopped. Holds the value of the flow rate or DC voltage. In addition, at least one of the values that change in relation to the motor speed including the motor speed or the command speed, the motor applied voltage, or the duty ratio of the inverter is used as the switching condition of the two speed control systems, After a predetermined time elapses from the time when the motor speed control by the PWM control system or the PAM control system becomes impossible, the system is forcibly switched to the PAM control system or the PWM control system.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a motor control device according to one embodiment of the present invention. This motor control device uses a rectifier circuit for converting the AC power supply 1 to DC, a chopper circuit and a smoothing circuit for increasing / decreasing the DC voltage by utilizing the switching operation of the switching element and the energy storage effect due to inductance, and A converter circuit 2 for controlling the magnitude, an inverter circuit 3 for converting a DC voltage to an AC power supply having a desired voltage, a motor control means 8 for controlling the speed of the brushless DC motor 4 according to a speed command, and a brushless DC motor 4, a converter control circuit 6 for controlling the converter circuit 2 in accordance with the corrected DC voltage signal and the converter ON / OFF signal from the motor control means 8, and a PWM signal from the motor control means 8. A driver 5 for driving the inverter circuit 3 with a signal and a drive signal;
And a current detection circuit 7 for detecting a power supply current input from the controller and transmitting the detected power supply current to the motor control means 8.

FIG. 3 shows a flowchart relating to the motor control processing of the motor control means 8. Motor control processing is roughly divided into a main processing that is repeatedly performed in a certain control cycle and an interrupt processing that is performed by an interrupt. The processing that is periodically performed includes speed calculation, converter operation determination, speed control, and stop. The interrupt processing includes drive signal generation and DC voltage correction calculation processing. The main process is a process that operates periodically. The initial setting is performed when the microcomputer is started and the initial setting is performed to start the motor. Pod,
The process includes a converter operation determination process for determining whether to operate the converter while the motor is being driven, a speed control process for determining the speed control and control system of the motor, and a stop process for stopping the motor. The interrupt processing is used for processing that must be performed in real time. In the drive signal creation processing, immediately after detecting the rotor position of the motor 4, the next drive signal (inverter transistor operation signal) output pattern is calculated and output. DC voltage calculation processing
The DC voltage value is detected in a cycle earlier than the main processing, the detected value is corrected by a DC voltage command value, and the calculation result is output.

FIG. 3 shows the internal structure of the motor control means 8. The motor control means 8 controls the speed of the brushless DC motor 4 from a speed signal calculated from an external speed command and a position detection signal of the position detection circuit 9. Here, the motor control means 8 uses a microcomputer, and all operations in the motor control means 8 are realized by software processing. The position detection signal detected by the position detection circuit 9 is input to the drive signal generation unit 83 and the speed calculation unit 84, and the drive signal generation unit 83 outputs a drive signal according to the position detection signal. Speed calculator 8
4 calculates the speed of the brushless DC motor 4 from the position detection signal and generates a motor stop signal when the motor is stopped. Converter operation determining section 82 outputs an operation permission signal according to the input current value from current detection circuit 7 and only when the input current value is equal to or greater than the set value. The DC voltage correction calculator 81 receives the DC voltage value and the DC voltage command value, and calculates a corrected DC voltage. Here, the corrected DC voltage value Ed ′ is calculated so as to output a certain value (DC voltage fixed command value Vr) when the DC voltage value Ed matches the DC voltage command value Ed *. The calculation of Expression 1) is performed. Ed ′ = (Ed / Ed *) × Vr (1) Here, the DC voltage correction calculation shown in (Equation 1) is performed by
Converter control circuit 6 is a DC voltage control circuit (not shown)
The DC voltage command value of the DC voltage control circuit is a fixed value (DC voltage fixed command value Vr), and by changing the detection gain of a DC voltage detection circuit (not shown), This is because DC voltage control is performed. If the DC voltage control circuit is configured to be able to input a DC voltage command value, it is not necessary to perform the DC voltage correction operation as described above. If the converter control circuit 6 has no DC voltage control circuit, a DC voltage control unit may be provided instead of the DC voltage correction calculation unit 81. The speed control means 80 calculates a deviation between the speed command signal and the speed signal, and calculates a PWM signal to the inverter circuit 3 and a DC voltage command value to the converter circuit 2 according to the speed deviation. Further, based on the motor stop signal and the speed signal, it is determined whether the speed control of the brushless DC motor 4 is performed by the PWM control by the inverter or the PAM control by the converter. This determination is performed by the PWM / PAM control determination unit 802. The DC voltage control calculation means 801 calculates the speed deviation, the PWM
A DC voltage command is calculated according to a control state signal, a motor stop signal, and an operation permission signal from a / PAM control determination unit 802, and a converter operation flag and a converter ON
/ OFF signal is output. Here, the DC voltage command has a minimum value when the control state signal is the PWM control, and has a DC voltage command value corresponding to the speed deviation when the control state signal is the PAM control. In other words, the DC voltage is increased or decreased according to the speed deviation. The converter ON / OFF signal turns on the converter when the motor stop signal indicates that the motor is operating and the operation permission signal indicates permission of the converter operation, and outputs a converter ON signal to the converter control circuit 6. As described above, converter circuit 2 starts operating and controls the DC voltage to the DC voltage command value. PWM duty calculator 8
03 is a speed deviation and PWM / PAM control determination unit 802
And outputs a PWM signal in accordance with the control state signal from. Here, when the control state signal is the PWM control, the PWM signal is a DC ratio according to the speed deviation. When the control state signal is P
In the case of the AM control, a conduction ratio of 100% is output. When the motor stop signal indicates that the motor is stopped, a duty ratio of 0% is output. In other words, energization of the motor is prohibited.

Next, a detailed operation when the control state is switched by the speed control means 80 of this embodiment will be described. First, FIG. 4 shows a relationship diagram when the rotation speed of the motor is plotted on the horizontal axis, and the DC voltage, the voltage applied to the motor, and the duty ratio of the inverter are plotted on the vertical axis. FIG. 4 (a) shows the case where the PWM control is used for PA
FIG. 4B is an explanatory diagram at the time of switching to M control, and FIG.
FIG. 4 is an explanatory diagram at the time of switching from control to PWM control. In addition,
The switching condition of the control system was a point in time when the actual rotation speed reached the switching set rotation speed N1. Here, the switching condition is not limited to the actual rotation speed, and may be any value related to the speed control of the motor, such as the voltage applied to the motor, the duty ratio of the inverter, and the command rotation speed. A case in which the PWM control shown in FIG. 4A is switched to the PAM control will be described. Assuming that the rotation speed command value is sufficiently larger than the switching set rotation speed N1, the motor accelerates after startup. When the motor rotation speed is N1 or less, the speed deviation shown in FIG. 3 is input to the PWM duty calculation unit 803,
The DC voltage control calculation means 801 sets the DC voltage command value to the minimum value of 150 V and outputs it. The duty ratio of the inverter gradually increases, and the rotation speed of the motor increases. Next, when the motor rotation speed reaches N1, PWM / PAM
The control determination unit 802 switches the control state signal to perform PAM control. As a result, the speed deviation shown in FIG. 3 is input to the DC voltage control calculation means 801 to increase the DC voltage. At this time, the duty ratio output from the PWM duty calculation unit 803 is mechanically increased to 100% according to a preset rising rate. After reaching 100%, maintain 100%. Here, since the motor speed is controlled by the DC voltage control calculating means 801 while the duty ratio is increasing, the amount of increase in the DC voltage command value is suppressed more than usual, and the gradient of the DC voltage is gentle. Become. In other words, the DC voltage changes according to the increase in the conduction ratio so that the increase in the number of rotations of the motor becomes constant. Assuming that the number of revolutions at which the conduction ratio reaches 100% is N2, only N2 or more increases the DC voltage. In other words, the normal P
AM control is performed. Here, the region of the rotation speeds N1 and N2 is a switching transition region.

Next, from PAM control shown in FIG.
The case of switching to WM control will be described. The rotation speed command value is set to a value sufficiently smaller than the switching rotation speed, and the switching rotation speed is set to N1 as in FIG. When the motor rotation speed is larger than N1, the speed deviation shown in FIG. 3 is input to the DC voltage control calculation unit 801 and the PWM duty calculation unit 803 outputs a duty ratio of 100%. The DC voltage gradually decreases, and the number of rotations of the motor decreases. next,
When the rotation speed reaches N1, the PWM / PAM control determination unit 802 switches the control state signal to perform PWM control.
As a result, the speed deviation shown in FIG. 3 is input to the PWM duty calculator 803, and the duty ratio is reduced. At this time, the DC voltage command value output from the DC voltage control calculation means 801 is mechanically reduced to the minimum DC voltage value according to a preset drop rate. After reaching the DC voltage minimum value, the DC voltage minimum value is maintained. Here, while the DC voltage command value is decreasing, the PWM duty calculation unit 803 controls the motor speed, so that the decrease in the duty ratio is suppressed more than usual, and the gradient of the duty ratio becomes gentler. . In other words, the conduction ratio changes in accordance with the decrease in the DC voltage so that the amount of decrease in the rotation speed of the motor is constant. Assuming that the number of revolutions at which the DC voltage command value has reached the minimum DC voltage value is N0, only N1 or less is a decrease in the conduction ratio. In other words, normal PWM control is performed. here,
The region of the rotation speeds N1 and N0 is a switching transition region.

As described above, in this embodiment, P
By gradually changing the DC voltage or the conduction ratio to the minimum value or the maximum value when switching between the WM control and the PAM control, it is possible to prevent a sudden change in the motor rotation speed at the time of switching even if the switching setting rotation speed is a fixed value. Further, in the case of the PWM control, the DC voltage can be operated at the minimum value, and in the case of the PAM control, the conduction ratio can be operated at the maximum value, so that the efficiency during operation can always be maintained at the maximum value.

Here, the set values of the conduction ratio and the DC voltage value are set to 1
Although the description has been made with reference to 00% and 150 V, this may be arbitrarily set depending on the conditions of the system used. Although the present embodiment is a converter circuit using a boost chopper circuit, the same operation can be performed in a step-down type or a step-up / step-down type.

Next, the speed control means 80 according to the present embodiment.
The switching operation of the PWM / PAM control will be described with reference to the flowchart shown in FIG. The processing shown in FIG. 5 is a part of the motor control processing performed in the motor control means 8 shown in FIG. 1, and is a part of the main processing shown in FIG. FIG.
In the PWM / PAM switching process, first, the process (A)
Then, whether the motor is stopped or not is determined by the speed calculation unit 84 shown in FIG.
From the motor stop signal from the controller. When the motor is stopped, the DC voltage control calculating means 8 of FIG.
01 stops the converter. Further, in (), the DC voltage control calculation means 801 sets the DC voltage command value to the minimum value of 150 V, and the PWM / PAM control determination unit 80
2 sets the control state signal to PWM control. Thereafter, the process exits from this process and returns to the main process. During the rotation of the motor, the converter operation determination unit 8 determines whether the converter is operating at (i).
The determination is made based on the operation permission signal from the control unit 2. At this time, if the converter is stopped, the process proceeds to (T) in the same manner as described above. When the converter is operating, the current control state is confirmed by the control state signal in (U), and in the case of PWM control (E)
Then, in the case of PAM control, the process proceeds to (S). If the PWM control is being performed, it is determined in (e) whether or not the control system is currently being switched by using the switching flag. This flag indicates “H” when switching is in progress. When the switching flag is "H", the process proceeds to (set), and when the switching flag is "L", the process proceeds to (o). Normally, since the switching flag is “L”, the process proceeds to (O), and it is determined whether or not the rotation speed has reached the switching setting rotation speed N1. change. If the number of rotations is less than the set switching speed N1, it is not necessary to change the control state, and the process proceeds to () and returns to the main process. In (), the control system is set to PAM control, and the control state is changed. At this time,
The control state signal output from the PWM / PAM control determination unit 802 changes to the PAM control state. In response to this signal, the DC voltage control calculation means 801 changes the DC voltage command value according to the speed deviation signal, and controls the speed of the motor 4. Next, the process proceeds to (g), where the PWM duty calculator 803 detects the current PWM duty value and determines that the duty value is 1
It is determined whether it is 00%. If the duty value is less than 100%, the process proceeds to step (c), the switching flag is set to “H”, and the current duty value is increased by 1%. Then (and) the process returns to the main process. Here, since the processes (G) to (K) are repeatedly performed in the cycle of the control process, the duty value increases by 1% every control cycle, and the duty value increases by 10%.
When it reaches 0%, the process proceeds to (), the switching flag is cleared, and () returns to the main process. On the other hand, when the control state is the PAM control in the process (U), the process proceeds to (S), and the switching flag is determined in the same manner as in (E). If the switching is in progress, the process proceeds to (C). Proceed to).
In (S), it is determined whether the current rotation speed is lower than the switching setting rotation speed N1. If the rotation speed is less than the switching setting rotation speed N1, the process proceeds to (S). Proceed to (and). If proceeding to (SU), change the control state to PA
Change from M control to PWM control. At this time, the control state signal is changed to the PWM control, and the PWM duty calculation unit 8
03 changes the PWM duty on the basis of the speed deviation signal, and controls the speed of the motor 4. Next, in (se), it is determined whether the current DC voltage value is 150 V or less.
In the following cases, the process proceeds to (C) to end the switching transition period, and the switching flag is cleared. When the DC voltage is 150 V or more, the process proceeds to (S), the switching flag indicating that the switching transition period is being set is set to “H”, and the DC voltage command value is reduced by 1 V in (T). The operations (se) to (ta) are performed by the DC voltage control calculation means 801. Since the above process is also repeated for each control cycle, the DC voltage is 150
When the voltage decreases to 150V, the value is maintained.
Although a DC voltage is used in the above process (set), a similar operation can be performed by using a DC voltage command value.

Next, two switch setting rotation speeds are provided, and PWM is set.
A switching operation (a switching operation with hysteresis provided) in which different switching speeds are used when switching from control to PAM control and when switching from PAM control to PWM control will be described. FIG. 6 shows a relationship diagram of the DC voltage, the motor applied voltage and the conduction ratio with respect to the motor rotation speed as in FIG. Here, N1 is a switching setting rotation speed 1 for switching from PWM control to PAM control, and N3 is a switching setting rotation speed 2 for switching from PAM control to PWM control.
It is. The difference between the rotational speeds of N1 and N3 may be such that the control system is not frequently switched. Also, the rotation speed N1
And the area of N3 is a switching transition area. As in FIG.
At the following rotation speeds, the DC voltage was controlled to 150 V and the PW
The duty ratio of the inverter is increased or decreased by the M control to control the speed of the motor. When the rotation speed exceeds N1 and increases, the control system switches from PWM control to PAM control. Each operation at this time is the same as the operation described with reference to FIG. At a rotation speed of N3 or more, the duty ratio of the inverter is maintained at 100%, the DC voltage is controlled by PAM control, and the speed of the motor is controlled. The motor decelerates and the rotation speed becomes N3
Is exceeded, the control system switches from the PAM control to the PWM control, and the speed control of the motor is performed with the duty ratio of the inverter. At this time, the DC voltage gradually and mechanically drops from the voltage value when the voltage exceeds N3 toward 150 V which is the minimum DC voltage setting value. After the DC voltage reaches 150 V, the DC voltage is maintained at 150 V, and the speed control of the motor is performed only by changing the duty ratio of the inverter.
In FIG. 6, the DC voltage and the conduction ratio have reached a certain value at N1 and N3 for the preparation of the diagram. However, in the actual case, the load condition and the power supply voltage fluctuate. There is little to do. As described above, two switch setting rotation speeds are set,
By adopting the hysteresis characteristic, the switching operation of the control system is suppressed in the vicinity of the switching set rotation speed, and stable motor speed control can be obtained.

Here, the flowchart in the switching operation provided with the hysteresis shown in FIG. 6 is performed by changing the switching set rotation speed of the process (S) shown in FIG. 5 to N3.
It is possible.

FIG. 7 shows another embodiment of the present invention. This embodiment is characterized in that a control state forcible change unit 804 is added inside the speed control unit 80 shown in FIG.
Although the case where the rotation speed of the motor has reached the switching setting rotation speed and the switching operation is possible has been described above, the rotation speed may not reach the switching setting rotation speed depending on the operating condition of the motor. Even if the rotation speed of the motor 4 does not reach the switching set rotation speed, the control state forcible change unit 804 can control the PWM / PAM control determination unit 8 based on the values of the PWM duty and the DC voltage.
02 forcibly outputs a control state switching signal to change the control state.

A detailed operation when the control state is switched by the speed control means 80 of this embodiment will be described. First, FIG.
FIG. 9 is an explanatory diagram of an acceleration operation under a high load, and FIG. 9 is an explanatory diagram of a deceleration operation under a light load. The horizontal axis indicates time, and the vertical axis indicates a DC voltage, a motor rotation speed, and a duty ratio of an inverter. FIG.
FIG. 9 shows a case where the motor starts at t0 and accelerates to 9000 min- ¹ and FIG. 9 shows a case where the command rotation speed is changed at t0 and the motor decelerates from 9000 min- ¹ to 3000 min- ¹ . In the case of FIG. 8, the PWM control area is from t0 to t2, and the PAM control area is after t2. In FIG. 9, the PAM control area is from t0 to t2, and the PAM control area is from t2.
This is the WM control area. Further, a period between t1 and t2 is a determination period. Here, when the load is heavy, the flow rate is 100%.
May occur, the actual rotation speed may not reach the switching set rotation speed. Further, when the load is light, the actual rotation speed may not reach the switching set rotation speed even when the DC voltage value reaches the minimum DC voltage set value. In such a case, FIGS. 4 and 5
In the switching method described above, since the control system cannot be switched, the rotation speed control thereafter cannot be performed. Therefore, a new switching determination method is required. One of the new switching determination methods is to measure the time when the actual rotation speed does not change despite the speed deviation (command rotation speed / actual rotation speed), and the measurement time is set in advance. This is a method in which the control system is forcibly switched when the elapsed time has passed. In FIGS. 8 and 9, the period from t1 to t2 is the above-described state, which is the determination period. In the case of FIG. 8, since the flow rate becomes 100% at t1, the rotation speed of the motor does not increase any more even though the actual rotation speed has not reached the command rotation speed. FIG.
In the case of (1), the DC voltage becomes the DC voltage minimum set value at t1, so that the motor speed does not further decrease even though the actual speed has not reached the command speed. In the above case, this state is determined, the time during which this state lasts is measured,
When the measurement time reaches the set time, the control system is forcibly switched. This time is t2. After that, speed control is performed by a normal control system to make the speed coincide with the commanded rotation speed. t2
Although the control system is switched at the point of time, since the duty ratio and the DC voltage value have already reached the maximum value or the minimum value, there is no change in the duty ratio and the DC voltage, and after the switching described in FIGS. There is no operation in the area. Here, the time required for the switching determination, in other words, the preset measurement time may be set to a time longer than the acceleration / deceleration rate during the PWM control or the PAM control. Further, in the above example, it was described that the number of rotations of the motor does not change. However, in an actual apparatus, there is a torque pulsation or a power supply pulsation, so that a slight rotation pulsation occurs. In an actual device, there is no problem if the rotation pulsation is set to be ignored. Also,
In the present embodiment, the time during which the actual rotation speed does not change is measured, but this is the time during which the duty ratio is maintained at 100%, the time during which the magnitude of the speed deviation is constant, or the DC voltage value is at the minimum value. Any value may be used as long as the value indicates that the current speed control system cannot control the speed of the motor, such as the time during which the motor speed is maintained.

Next, the speed control means 80 according to this embodiment
The switching operation of the PWM / PAM control will be described with reference to flowcharts shown in FIGS. FIG. 10 is almost the same as FIG. 5 described above.
Only the processing part added after (and). FIG.
In FIG. 11, the processing shown in FIG. 11 is added between the processing performed directly (and) from (O) or (S).
Therefore, the process shown in FIG. 10 is the same as the content described in FIG. 5, and a description thereof will be omitted. Only FIG. 11 will be described. The process of FIG. 11 is a process performed within the determination period (t1 to t2) illustrated in FIG. 8 or FIG. In other words,
When the rotation speed does not reach the switching setting rotation speed, the PWM duty becomes 100% (in the PWM control state) or the DC voltage becomes 150 V or less (in the PAM control state). Next, the control state is forcibly switched. In the process (O) of FIG. 10, when the rotation speed is less than the switching set rotation speed, the process proceeds to (N) of FIG. Here, the state is the PWM control state, and FIG.
In the state between t1 and t2 shown in FIG. 7 and the state in which the PWM duty is 100%. In the process (N), it is determined whether the current duty is 100%, and 100%
If it is less, the process proceeds to () as in FIG. 5 and shifts to the main process. In the case of 100%, the process proceeds to (ii) to determine the difference between the current rotation speed and the command rotation speed. If the current rotation speed is equal to or higher than the command rotation speed, the process proceeds to () in the same manner as described above, and shifts to the main process. If the current rotation speed does not reach the command rotation speed, the processing shown in FIG. Proceed to (?) To forcibly switch to PAM control. The subsequent operation repeats the same operation as described with reference to FIG. Conversely, in the process (S) of FIG. 10, when the rotation speed is equal to or more than the switching set rotation speed, the process proceeds to (H) of FIG. Here, the PAM control state is a state between t1 and t2 shown in FIG. 9, and the DC voltage is 150V. Processing (is)
Then, it is determined whether the current DC voltage is 150 V, and 150 V
If so, the process proceeds to () in the same manner as in FIG. If the voltage is equal to or lower than 150 V, the process proceeds to (h) to determine the difference between the current rotation speed and the command rotation speed. If the current rotation speed is equal to or less than the command rotation speed, the process proceeds to () in the same manner as described above, and shifts to the main process. Go ahead and force PWM
Switch to control. The subsequent operation repeats the same operation as described with reference to FIG. The above processing is performed by the control state forced change unit 804 shown in FIG. By the above processing, the control state can be reliably changed even when the rotation speed does not reach the switching set rotation speed at the time of high load or light load, and the control is not lost.

FIG. 12 shows a process obtained by adding a time factor to the process shown in FIG. In other words, the switching condition of the control system shown in FIG.
The control system is changed when the operation is continued 0 times. Although the change of the control state is slightly delayed by the above operation, it can be confirmed that the switching condition has been reliably reached. In this case, the control state compulsory change unit 804 shown in FIG. 7 needs to have a counter function. Processing shown in FIG.
(H) and (H) are the same as in FIG. In addition, processing (nu)
(Ne) (no) (mu) and processing (fu) (he) (ho) (me) are the same, except for the final destination, so processing (nu) (ne) ( Only ()) will be described. The process (nu) monitors the value of the counter, and when the counter reaches 10, the process proceeds to ().
If the counter is less than 10, proceed to the process (ne),
At (ne), the counter is incremented by one. After counting up, the process proceeds to () in FIG. 10 and returns to the main process. In the process (), the counter is cleared, and the process proceeds to the control system switching process. Here, the process proceeds to the process (?) In FIG.
Change to PAM control. The process (M) clears the counter in the same manner as the process (NO), proceeds to () in FIG. 10, and returns to the main process. In the processes (ii) and (ii), the rotational speed and the command rotational speed are compared. However, the speed deviation signal may be detected, and it may be determined whether the speed deviation signal is positive or negative.

FIG. 13 shows another embodiment of the present invention.
The present embodiment is characterized in that a switching transition period canceling unit 805 is provided inside the speed control unit 80 shown in FIG. 3, and the rotation speed command value and the actual rotation speed during the switching transition region shown in FIG. 4. Are matched, and when the rotation speed no longer changes, the period of the switching transition is stopped.

A detailed operation when the control state is switched by the speed control means 80 of this embodiment will be described. First, FIG.
4 is an explanatory diagram of the switching operation when the rotation speed command value and the actual rotation speed match during the period of the switching transition region shown in FIG. 4 and the rotation speed no longer changes, and the horizontal axis indicates time. The vertical axis shows the DC voltage, the motor speed, and the duty ratio of the inverter. In FIG. 14, at the time of speed increase, in other words,
The operation at the time of switching from PWM control to PAM control will be described. From t0 to t1, the rotation speed is controlled according to the command rotation speed by the PWM control. When the command rotation speed is changed at t1 and reaches N * 1, the flow rate increases toward it and the rotation speed increases. When the rotation speed exceeds the switching setting rotation speed at t2, the speed control system sets the PW as in FIG.
The control is switched from the M control to the PAM control. At this time, the duty ratio mechanically gradually increases from the duty ratio at t2 toward the 100% duty ratio. However, at t3, the flow rate becomes 100
The actual rotation speed matches the command rotation speed before reaching%.
In the case of FIG. 4, since the flow rate mechanically increases to 100%, the actual rotation speed exceeds the command rotation speed. In addition, it is conceivable to lower the DC voltage because the actual rotation speed exceeds, but since the minimum value of the DC voltage is limited, in the worst case, it may not be possible to perform control according to the command rotation speed. Therefore, when the actual rotation speed matches the command rotation speed, the increase or decrease of the operation amount before switching is stopped.
At t3, the increase of the duty ratio is stopped, and thereafter, the speed control of the motor is performed only by changing the DC voltage. The conduction ratio maintains the value at time t3. Next, at the time of deceleration, in other words, PAM
The operation at the time of switching from the control to the PWM control will be described. When the command speed changes to N * 2 at t4, the DC voltage is reduced. When the actual rotation speed exceeds the switching setting rotation speed at t5, the PAM control is switched to the PWM control as described above, and the DC voltage mechanically drops as in FIG. Here, if the actual rotation speed matches the command rotation speed before the DC voltage reaches the minimum DC voltage value at t6, the reduction of the DC voltage is stopped as described above, and thereafter, this value is maintained. With the above operation, the speed control near the switching value between the PWM control and the PAM control can be stabilized.

Next, the speed control means 80 according to this embodiment
The switching operation of the PWM / PAM control will be described with reference to the flowchart shown in FIG. FIG. 15 is almost the same as the processing shown in FIG. 5, and only different points are the processing (ma) and (mi). Otherwise, the same operation as in FIG. 5 is performed. The process shown in FIG. 15 changes the control state, and during the control state transition period (t2 to t3 or t5 to t3 in FIG. 14).
The control state transition period ends when the actual rotation speed matches the command rotation speed in 6). Therefore, FIG.
The process (ma) is inserted between the processes (ka) and (g), and the process (mi) is inserted between the processes (su) and (se). In the process (F), the actual rotational speed is compared with the commanded rotational speed, and when the actual rotational speed reaches the commanded rotational speed, the process proceeds to the end in order to end the switching transition period. Here, if the actual rotation speed has not reached the command rotation speed, the process proceeds to (g), and the switching transition period is maintained. Since the process (mi) performs the same operation, the description is omitted. As described above, in the present embodiment, if the actual rotation speed reaches the command rotation speed even during the control system switching transition period, the switching transition period can be stopped, and the motor can be controlled according to the situation.

Next, FIG. 16 shows a configuration diagram of an air conditioner control circuit in which the present invention is applied to compressor control of an air conditioner. This air conditioner control circuit connects the motor 4 of the motor control device shown in FIG. 1 directly to the compressor 10 inside the outdoor unit of the air conditioner, and controls the compressor 10 according to the speed command signal from the temperature control means 11 inside the outdoor unit. This is a configuration for performing rotation speed control. The temperature control unit 11 calculates a temperature deviation from a temperature command from a remote controller or the like and a room temperature from the room temperature sensor 12, and calculates a speed command signal by proportional integral control. This speed command signal is transmitted from the indoor unit to the outdoor unit, and is transmitted to the motor control means 8 inside the outdoor unit. The motor control means 8 controls the speed of the motor 4 according to the speed command signal sent from the indoor unit. By the above operation, the compressor is driven, and control is performed to the room temperature according to the temperature command. As described above, if the circuit configuration of the embodiment of the present invention is directly applied to the control of the compressor drive motor of the air conditioner, and the rotational speed command value of the compressor drive motor is calculated from the temperature command value and the room temperature, a wide range is obtained. It is possible to realize a high-capacity air conditioner that can be controlled at a high speed.

As described above, the embodiment of the present invention has been described in the case of using the 120-degree conduction type trapezoidal wave control of the brushless DC motor, but the same operation can be performed in the 180-degree conduction type sine wave control and the control of the AC motor. It is possible. In this case, the chopper signal may be gradually brought closer to a predetermined chopper pattern. Further, in the embodiment of the present invention, a DC power supply is created by using a rectifier circuit and a smoothing circuit for an AC power supply. However, in a system in which a DC power supply can be directly used, for example, an electric vehicle or a system using a solar cell is used. When applied, the rectifier circuit and the smoothing circuit are not required, and can be implemented by directly connecting a boost chopper circuit to a DC power supply.

[0025]

As described above, according to the present invention,
By gradually changing the DC voltage and the duty ratio to the minimum value or the maximum value when switching between the PWM control and the PAM control, it is possible to prevent a sudden change in the motor speed at the time of switching. Further, in the case of the PWM control, the DC voltage is operated at the minimum value, and in the case of the PAM control, the conduction ratio is operated at the maximum value, so that each speed control system can operate with maximum efficiency. Furthermore, by giving the switching setting condition a hysteresis characteristic, fluctuations at the time of switching near the switching point of the speed control system are suppressed, and stable motor speed control can be obtained. In addition, the control state forcible change processing allows the control state to be reliably changed even when the rotation speed does not reach the switching set rotation speed under a high load or a light load, thereby preventing the control from being lost. it can.
Further, if the actual rotation speed of the motor reaches the commanded rotation speed during the switching transition period of the speed control system by the PWM control or the PAM control, the switching transition period is stopped, so that the motor control according to the situation becomes possible. Speed control near the switching value of the speed control system can be stabilized. Also, by applying the present invention to control of a compressor driving motor of an air conditioner, a high-performance air conditioner that can be controlled in a wide range can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a motor control device according to an embodiment of the present invention.

FIG. 2 is a motor control processing diagram according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a motor control unit according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a PWM / PAM control switching operation according to an embodiment of the present invention.

FIG. 5 is a PWM / PAM control switching processing diagram according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a switching operation provided with hysteresis according to an embodiment of the present invention.

FIG. 7 is a configuration diagram of a motor control unit according to another embodiment of the present invention.

FIG. 8 is a diagram illustrating a switching operation under a high load according to another embodiment of the present invention.

FIG. 9 is an explanatory diagram of a switching operation at a light load according to another embodiment of the present invention.

FIG. 10 shows a PWM / PAM according to another embodiment of the present invention.
Control switching process diagram

FIG. 11 shows a PWM / PAM according to another embodiment of the present invention.
Control switching process diagram

FIG. 12 shows a PWM / PAM according to another embodiment of the present invention.
Control switching process diagram

FIG. 13 is a configuration diagram of a motor control unit according to another embodiment of the present invention.

FIG. 14 shows a PWM / PAM according to another embodiment of the present invention.
Illustration of control switching operation

FIG. 15 shows a PWM / PAM according to another embodiment of the present invention.
Control switching process diagram

FIG. 16 is a configuration diagram when the present invention is applied to air conditioner control.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... AC power supply, 2 ... Converter circuit, 3 ... Inverter circuit, 4 ... Motor, 5 ... Driver, 6 ... Converter control circuit, 7 ... Current detection circuit, 8 ... Motor control means, 9 ... Position detection circuit, 10 ... Compression Machine, 11 ... temperature control means, 12 ...
Temperature sensor, 80: speed control means, 81: DC voltage correction calculation section, 82: converter operation determination section, 83: drive signal creation section, 84: speed calculation section, 801: DC voltage control calculation section, 802: PWM / PAM Control determination unit, 803
... PWM duty calculator, 804... Control state forced change means, 805.

Claims (7)

[Claims] 1. A converter comprising a rectifier circuit and a smoothing circuit for converting an AC power supply to DC, a chopper circuit for increasing / decreasing a DC voltage, an inverter for converting an output of the converter to AC, and a drive driven by an output of the inverter. A DC voltage command to PWM control for controlling the speed of the motor and DC voltage control means for controlling the chopper circuit, and output a DC voltage command to a control circuit of the inverter and a speed control of the motor. Of PAM control that performs
A motor control device having two speed control systems and a speed control means for switching between the two speed control systems depending on a control state, wherein the motor speed includes a motor speed or a command speed, a motor applied voltage, or a duty ratio of an inverter. At least one of the values that change in relation to is used as a switching condition for the two speed control systems, and a switching transition area is provided, and when the two speed control systems are switched,
A motor control device, wherein the duty ratio of the inverter and the DC voltage are changed according to a preset rate in the switching transition area. 2. The motor control device according to claim 1, wherein at least two different values are set as the switching condition, and a switching transition region of the two speed control systems is provided to have a hysteresis characteristic. 3. The switching transition area according to claim 1, wherein when the motor speed is switched from a PWM control system to a PAM control system, the motor speed control is performed by the PAM control system. In step (1), the duty ratio of the inverter is changed to a set value according to a preset rate, and when switching from the PAM control system to the PWM control system is performed, the DC voltage by the PAM control system is controlled while controlling the motor speed by the PWM control system. A motor control device for changing to a predetermined value according to a preset rate in a switching transition area. 4. The method according to claim 1, wherein when the actual speed of the motor reaches the command speed when the two speed control systems are switched, the duty ratio of the inverter or the DC voltage is set in advance. A motor control device which stops changing in accordance with a set rate and holds a value of a duty ratio or a DC voltage of the inverter at the time of the stop. 5. A converter comprising a rectifier circuit and a smoothing circuit for converting an AC power supply to a DC, a chopper circuit for increasing / decreasing a DC voltage, an inverter for converting an output of the converter to an AC, and a drive driven by an output of the inverter. A DC voltage command to PWM control for controlling the speed of the motor and DC voltage control means for controlling the chopper circuit, and output a DC voltage command to a control circuit of the inverter and a speed control of the motor. Of PAM control that performs
A motor control device having two speed control systems and a speed control means for switching between the two speed control systems depending on a control state, wherein the motor speed includes a motor speed or a command speed, a motor applied voltage, or a duty ratio of an inverter. Is used as a condition for switching between the two speed control systems, and is set in advance from a point in time when it becomes impossible to control the speed of the motor by the current PWM control system or PAM control system. A motor control device for forcibly switching to a PAM control system or a PWM control system after a predetermined time has elapsed. 6. The motor according to claim 5, wherein the current PWM control system or the PAM control system controls the motor speed when the actual speed of the motor cannot reach the command speed within a predetermined time set in advance. PAM control system or P
A motor control device characterized by switching to a WM control system. 7. The motor according to claim 1, wherein a speed command value of the motor is calculated from the room temperature set temperature and the room temperature, and the speed of the compressor driving motor of the air conditioner is controlled in accordance with the speed command value. A motor control device characterized by the above-mentioned.