JP2510093Y2 - Brushless DC motor drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a brushless DC motor drive device, and in particular, to a brushless DC motor for stable starting of a brushless DC motor used for a compressor motor or the like. The present invention relates to a motor drive device.

[Prior Art] FIG. 4 is an overall configuration diagram showing a conventional brushless DC motor driving device disclosed in, for example, JP-A-61-1290, and FIG. 5 is a diagram showing a conventional brushless DC motor driving device. It is a characteristic view which shows the time-dependent change of an output voltage.

In the figure, (1) is an inverter circuit that converts direct current to alternating current, and switching elements (TU), (TV), (T
W), (TX), (TY), (TZ) and diode (DU),
It is composed of (DV), (DW), (DX), (DY), (DZ). (2) is a brushless DC motor, (3) is a position detection circuit that detects the position of the rotor by the voltage between the terminals of the armature winding of the brushless DC motor (2), and (4) is each inverter circuit (1). Switching element (TU),
…, (TZ) to supply the operation signal, inverter circuit (1)
Is a control circuit for controlling the operation of.

The conventional brushless DC motor is configured as described above. This driving operation will be described below.

First, the switching signal corresponding to the frequency data and the output voltage data preset by the control circuit (4) is output to each switching element (T) of the inverter circuit (1).
It is output to U), ..., (TZ). Upon receiving this signal, the inverter circuit (1) operates. Then, the DC power applied to the inverter circuit (1) is converted into AC of a predetermined frequency and supplied to the brushless DC motor (2),
The brushless DC motor (2) starts low frequency activation.

An induced voltage is generated in the armature winding as the rotation speed of the rotor of the brushless DC motor (2) increases. The position detection circuit (3) detects the position of the rotor by the voltage between the terminals of the armature winding, which is the induced voltage. Then, the detection signal of the position detection circuit (3) is transmitted to the control circuit (4).

The control circuit (4) compares the switching signal that has been transmitted up to that time with the detection signal from the position detection circuit (3). Then, if they are synchronized with each other for a certain period of time and output voltage (point A in FIG. 5), the other control, that is, the asynchronous operation is switched to the synchronous operation, and the drive of the brushless DC motor (2) is continued.

[Problems to be Solved by the Invention] In the conventional brushless DC motor driving device as described above, in order to drive the brushless DC motor (2) from the stopped state, the inverter is started as another control system and then the synchronous system is driven. The drive is continued by switching to. In particular, when the inverter is started as a separate system, the operation of the inverter circuit (1) is performed according to preset predetermined data.

As a conventional example of this type of technology, there is Japanese Patent Publication No. 52-34726 in addition to the above-mentioned publication.

In this type of conventional brushless DC motor drive,
Even when the resistance value of the armature winding of the brushless DC motor (2) changes and the load changes, the constant output voltage always switches from the other braking operation to the synchronous operation. In particular, the change in the load is caused by the temperature change. For this reason, there is a problem in that when the load changes, a start-up failure occurs and the low-frequency synchronous start-up cannot be surely performed.

As a technique considering this point, Japanese Patent Laid-Open No. 62-95997 discloses controlling the applied voltage according to the temperature of the stepping motor. However, it is difficult to directly measure the winding temperature of the stepping motor, and as a practical problem, it is not possible to distinguish between the temperature immediately after operation and the high temperature state such as summer, and the temperature of the motor itself is estimated as the winding temperature. It had been.

Especially after running the brushless DC motor (2) for a long time,
There was a problem when the brushless DC motor (2) was once stopped and then restarted while the brushless DC motor (2) was still heated.

Therefore, the present invention has been made in order to solve such a problem, and ensures reliable low-frequency synchronous start even when the load of the brushless DC motor changes or when restarting immediately after power-off. An object of the present invention is to obtain a brushless DC motor drive device capable of performing

[Means for Solving Problems] A brushless DC motor drive device according to the present invention is
When the brushless DC motor is started by using the inverter as another system and the brushless DC motor is at a predetermined speed or more,
In a brushless DC motor drive that detects the position of the rotor with a position detection circuit based on the voltage between the terminals of the armature winding and continues driving synchronously, detects the temperature around the installation part of the brushless DC motor drive. Ambient temperature detector, a motor temperature detector for detecting the temperature of the brushless DC motor, the load of the brushless DC motor is calculated from the temperature detected by the ambient temperature detector and the motor temperature detector, depending on the load And a control circuit for determining the output voltage data and starting the brushless DC motor by this output voltage.

[Operation] In the brushless DC motor drive device of the present invention, the ambient temperature of the installation portion of the brushless DC motor drive device is detected by the ambient temperature detector, the temperature of the brushless DC motor is detected by the motor temperature detector, and Since the control circuit controls the output voltage at the start of the brushless DC motor by using the temperatures detected by the ambient temperature detector and the motor temperature detector, heating of the brushless DC motor or changes in the ambient temperature, etc. Thus, when the load of the brushless DC motor changes, the brushless DC motor is started with the output voltage according to the change of the load.

[Embodiment] FIG. 1 is an overall configuration diagram showing a brushless DC motor drive device according to an embodiment of the present invention, and FIG. 2 is a flow chart showing an operation of the brushless DC motor drive device according to an embodiment of the present invention. FIG. 3 is a characteristic diagram showing changes with time in the output voltage of the brushless DC motor drive device according to the embodiment of the present invention. In the figure, (1) to (3) are the same or corresponding components as those of the conventional example.

In the figure, (5) is a control circuit including a microcomputer for controlling the operation of the inverter circuit (1),
(6) is an ambient temperature detector that detects the temperature around the installation portion of the brushless DC motor drive device, and (7) is a motor temperature detector that detects the temperature of the brushless DC motor (2). The control circuit (5) has a function of controlling the output voltage at the time of starting the brushless DC motor (2) using the temperatures detected by the ambient temperature detector (6) and the motor temperature detector (7). ing.

The control operation of the brushless DC motor drive device of this embodiment will be described with reference to the flowchart of the "low frequency starting routine" in FIG.

Before starting the low frequency start of the brushless DC motor (2), first, in step S1, the ambient temperature detector (6) detects the temperature around the installation portion of the brushless DC motor drive device. This detected temperature is stored in the memory of the control circuit (5) in step S2. Next, in step S3, the temperature of the brushless DC motor (2) is detected by the motor temperature detector (7). The detected temperature is stored in the memory of the control circuit (5) in step S4. Then, in step S5, the load of the brushless DC motor (2) is calculated using the temperatures detected by the ambient temperature detector (6) and the motor temperature detector (7). For example, when the ambient temperature and the motor temperature are high, the armature winding resistance is large and the load is large. In the opposite case, the load is small. Depending on this load change, step
The output voltage data is determined in S6. For the calculation of the load and the determination of the output voltage data, the characteristic value calculated and determined in advance in the memory of the control circuit (5) based on the stored data is stored. With this output voltage, the low frequency start of the brushless DC motor (2) is started in step S7, and this routine is ended.

As described above, in the brushless DC motor drive device of this embodiment, the brushless DC motor (2) is heated,
When the load of the brushless DC motor (2) changes due to the change of the ambient temperature or the like, the output voltage can be changed according to the change of the load to start the brushless DC motor (2). That is, when the load of the brushless DC motor (2) is large, the output voltage is high (point B in FIG. 3), and when the load is small, the output voltage is low (FIG. 3C).
Point), shift from other-type operation to synchronous operation. Therefore, the brushless DC motor (2) can be smoothly driven, and the failure in starting the brushless DC motor (2) is reduced, so that stable low-frequency synchronous startup can be reliably performed. Therefore, the brushless DC motor drive device is highly reliable.

In addition, since the output voltage changes according to the load of the brushless DC motor (2), when the load is small, a low output voltage is sufficient, and power saving can be promoted.

In particular, the control circuit (5) calculates the load of the brushless DC motor (2) from the temperatures detected by the ambient temperature detector (6) and the motor temperature detector (7), and outputs the output voltage data corresponding to the load. Since the output voltage is determined and the brushless DC motor (2) is started, the ambient temperature detector (6) and the motor temperature detector (7) increase the winding temperature of the brushless DC motor (2). Can be estimated, restart can be determined immediately after power-off, and stable low-frequency synchronous startup can be reliably performed.

[Effects of the Invention] As described above, the brushless DC motor drive device of the present invention detects the temperature around the installation portion of the brushless DC motor drive device by the ambient temperature detector to detect the temperature of the brushless DC motor. To detect, and
The control circuit controls the output voltage at start-up of the brushless DC motor using each temperature detected by the ambient temperature detector and the motor temperature detector, so that the brushless DC motor can be heated or the ambient temperature can change. When the load changes, the brushless DC motor can be started with the output voltage corresponding to the change in the load, so that the transition from the other braking operation to the synchronous operation can be smoothly performed. Therefore, the brushless DC motor can be stably and reliably started at a low frequency synchronously, and the brushless DC motor drive device is highly reliable.

In particular, the load of the brushless DC motor is calculated from each temperature detected by the ambient temperature detector and the motor temperature detector, the output voltage data corresponding to the load is determined, and the brushless DC motor is started by this output voltage. Therefore, the ambient temperature detector and the motor temperature detector can be used to estimate the increase in the winding temperature of the brushless DC motor, to determine the restart immediately after the power is cut off, and to restart the operation in the heating state. Even if it does, stable low-frequency synchronous activation can be surely performed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a brushless DC motor driving device according to an embodiment of the present invention, and FIG. 2 is a flowchart of a "low frequency starting routine" showing an operation of the brushless DC motor driving device of the present invention. FIG. 4 is a characteristic diagram showing changes with time in the output voltage of the brushless DC motor drive device of this embodiment, FIG. 4 is an overall configuration diagram showing a conventional brushless DC motor drive device, and FIG. 5 is a conventional brushless DC motor drive device. 3 is a characteristic diagram showing the change over time of the output voltage of FIG. In the figure, 2: brushless DC motor 3: position detection circuit 5: control circuit 6: ambient temperature detector 7: motor temperature detector. In the drawings, the same reference numerals and symbols indicate the same or corresponding parts.

Claims (1)

(57) [Scope of utility model registration request] Claim: What is claimed is: 1. A brushless DC motor is started by using an inverter as another control system, and the brushless DC motor detects the position of the rotor by a voltage between terminals of an armature winding at a predetermined number of revolutions or more by a position detection circuit, and is a synchronous type. In a brushless DC motor drive device that continues to drive at, an ambient temperature detector that detects the temperature around the installation portion of the brushless DC motor drive device, and a motor temperature detector that detects the temperature of the brushless DC motor, A control circuit for calculating the load of the brushless DC motor from the temperatures detected by the ambient temperature detector and the motor temperature detector, determining output voltage data according to the load, and starting the brushless DC motor with this output voltage. A brushless DC motor driving device comprising: