JPH0744871B2 - Controller for DC motor without commutator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for a non-commutator DC motor that rotates a magnet rotor by a back electromotive force induced in an armature winding.

2. Description of the Related Art In recent years, non-rectifier DC motors have been used in various fields because of their high efficiency and the fact that the number of revolutions can be easily changed by changing the applied voltage. However, in general, a position detecting sensor such as a Hall element is required to operate the non-rectifier DC motor by controlling the operation timing and time of the semiconductor switching element. However, when you want to use a non-commutator DC motor in a place where the operating environment is very bad such as high temperature, high pressure, and oil such as an electric compressor,
There was a problem with the reliability of the position detection sensor. Therefore, in recent years, various methods have been proposed in which the relative position of the magnet rotor is detected from the back electromotive force of the armature winding and the semiconductor switching element is controlled by the signal.

An example of the conventional controller for a non-rectifier DC motor described above will be described below with reference to the drawings.

FIG. 3 shows a conventional controller for a DC motor without commutator. Reference numeral 1 is a DC power supply, and 2 is a semiconductor commutator device formed by connecting _six semiconductor switching elements S _{1 to} S ₆ in a three-phase bridge connection. Reference numeral 3 is a non-commutator DC electric motor having an armature winding 4 and a magnet rotor 5. 6 is a back electromotive force detection circuit which inputs the winding voltages V _{A to} V _C of the armature winding 4,
Reference numeral 7 is a drive circuit which inputs the output of the back electromotive force detection circuit ₆ and drives the semiconductor switching elements S _{1 to} S ₆ of the semiconductor commutator device 2. Reference numeral 8 is a resistor inserted between one end of the DC power supply 1 and one end of the input of the semiconductor commutator, and 9 is a current detection circuit for detecting a current by the voltage generated at both ends of the resistor 8. Reference numeral 10 is a starting circuit for operating the drive circuit 7 at the time of starting.

The operation of the control device for the DC motor without commutator configured as described above will be described below.

First, since the back electromotive voltage is not generated in the armature winding 4 when the motor is stopped, the relative position of the magnet rotor 5 in the back electromotive voltage detection circuit 6 cannot be detected. Therefore, the drive circuit 7 is operated by the starting circuit 10. , The semiconductor switching elements S _{1 to} S ₆ of the semiconductor commutator device 2 are controlled to excite the armature winding 4. A rotating magnetic field is generated inside the armature by sequentially switching this excitation. The magnet rotor 5 rotates in synchronization with this rotating magnetic field. The number of rotations of the magnet rotor 5 can be increased by sequentially increasing the frequency of the rotating magnetic field. When the number of rotations of the magnet rotor 5 increases and a counter electromotive voltage of the armature winding is generated as the motor rotates and the counter electromotive voltage detection circuit 6 becomes able to detect the relative position of the magnet rotor 5, the next reverse occurs. The drive circuit 7 is controlled by the electromotive voltage detection circuit 6. Since the back electromotive force detection circuit 6 takes only the components of the back electromotive force from the winding voltages V _{A to} V _C of the armature winding 4 to detect the relative position of the magnet rotor 5, a position detection sensor such as a hall element is detected. Stable operation can be obtained as in the case of using. When the voltage generated across the resistor 8 exceeds a certain value (that is, an overcurrent flows), the current detection circuit 9 outputs a signal to stop the operation of the drive circuit and stop the magnet rotor 5. When this non-commutator DC motor is locked due to an external factor or the like, the magnet rotor 5 is stopped by the operation of the current detection circuit 9 to protect the armature winding 4 and the semiconductor switching elements S _{1 to} S ₆ . .

Problems to be Solved by the Invention However, the above configuration has the following problems. When the position is detected by the counter electromotive voltage, the counter electromotive voltage generated in the armature winding 4 becomes 0 V when locked, so that the operation is performed in the closed loop of the counter electromotive voltage detection circuit 6, the drive circuit 7, and the semiconductor commutator device 2. , Armature winding 4
Positive feedback is applied by the L component of and oscillates at a high frequency (about 500 Hz or more in a 100 W class non-rectifier motor) inside the closed loop. The current at the time of this oscillation is smaller than the current that flows through the armature winding when a normal position detection sensor is used, that is, DC. That is, the L component of the armature winding 4 suppresses the current. Here, when the maximum rated current of the non-rectifier electric motor 3 is small and the current at the time of locking is larger, the protection at the time of locking can be performed as it is in the conventional example. However, depending on the capacity of the motor, as shown in Fig. 4, the current during motor operation
I ₁ is larger than the current I ₂ when the motor is locked. In such a case, the conventional method cannot protect the lock. Therefore, there is a problem that the motor winding and the semiconductor switching element are destroyed in the worst case without being released from the locked state.

In view of the above problems, the present invention can accurately detect the locked state even when the electric current during the operation of the electric motor is larger than the electric current when the electric motor is locked and can stop the operation. A control device for a DC motor is provided.

Means for Solving the Problems A commutatorless DC motor of the present invention for solving the above problems is a counter electromotive voltage detection circuit for detecting a relative position of a magnet rotor by a counter electromotive voltage generated in an armature winding. And a drive circuit for driving the semiconductor switching element of the semiconductor commutator device by the output of the counter electromotive voltage detection circuit, and the detected frequency of the output of the counter electromotive voltage detection circuit becomes higher than a certain frequency. And a frequency detection circuit for stopping the operation of the drive circuit.

Operation According to the present invention, due to the above configuration, the back electromotive voltage of the armature winding is not generated when the magnet rotor is locked, and the back electromotive voltage detection circuit, the drive circuit, and the semiconductor commutator device are closed loop. Utilizing the fact that positive feedback is applied inside and oscillates at a high frequency, and when the output frequency of the back electromotive voltage detection circuit becomes higher than a certain frequency, the operation of the drive circuit is stopped to release from the locked state. Is performed to protect the armature winding and the semiconductor switching element.

Example Hereinafter, a controller for a non-rectifier DC motor according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a controller for a DC motor without commutator according to an embodiment of the present invention. In FIG. 1, 1 to 10 are the same as those in the conventional example, and therefore the description thereof is omitted. Reference numeral 11 is a frequency detection circuit that controls the drive circuit 7 by using the output of the back electromotive voltage detection circuit 6 as an input.

The operation of the control device for the commutatorless motor configured as described above will be described below with reference to FIGS. 1 and 2.

First, since the starting method and the steady operation method in FIG. FIG. 2A shows the input / output characteristics of the frequency detection circuit 11. The input frequency is
_{When the} frequency is lower than ₀ , the output is "H" level, and when the frequency is lower than _{0, the} output is "L" level. Also f ₁
Is the maximum frequency when the non-rectifier motor is operating normally, ₂ is the oscillation frequency due to the closed loop of the back electromotive force detection circuit 6 and the drive circuit 7 and the semiconductor commutator device 2 when locked, and ₀ is It is set so that ₁ < ₀ < ₂ . 2b and 2c show examples of the waveforms at points A and B in FIG. Up to time t ₁ , the commutatorless DC motor 3 is in steady operation, a signal of frequency ₁ is generated at point A, and an “L” level signal is output at point B according to FIG.
The drive circuit 7 is continuously operated. Now, at time t _1, it is assumed that the non-rectifier DC motor 3 is locked for some reason. At this time, the back electromotive voltage is not generated in the armature winding 4, and the signal at the point A has a high frequency _{2 as} shown in FIG. 2b due to the closed loop of the back electromotive voltage detection circuit 6, the drive circuit 7, and the semiconductor commutator device 2. Oscillates at. Therefore, at the point B, the "H" level signal is output according to FIG. 2a, and the drive circuit 7 is stopped at time t ₂ to stop all the operations.

As described above, according to this embodiment, the frequency detection circuit for detecting the output frequency of the counter electromotive voltage detection circuit 6 and for stopping the operation of the drive circuit 7 when the detected frequency becomes higher than a certain frequency is provided. Therefore, even if the current during motor operation is larger than the current when the motor is locked, the operation is stopped after confirming that the output frequency of the back electromotive force detection circuit 6 is high, so the locked state can be released. The motor winding and the semiconductor switching element can be protected.

EFFECTS OF THE INVENTION As described above, according to the present invention, the counter electromotive voltage detection circuit for detecting the relative position of the magnet rotor by the counter electromotive voltage generated in the armature winding, and the semiconductor switching element by the output of the counter electromotive voltage detection circuit. By providing a drive circuit for driving, and a frequency detection circuit that detects the frequency of the output of the counter electromotive voltage detection circuit and stops the operation of the drive circuit when the detected frequency becomes higher than a certain frequency, Even when the current during operation of the non-rectifier DC motor is larger than the current during lock, the high frequency generated in the closed loop of the counter electromotive voltage detection circuit, the drive circuit, and the semiconductor commutator device during lock is controlled. It is possible to stop the non-commutator motor by detecting it and surely detecting the locked state.

[Brief description of drawings]

FIG. 1 is a block diagram of a controller for a non-rectifier DC motor according to an embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation of FIG. 1, and FIG. 3 is a control for a conventional non-rectifier DC motor. FIG. 4 is a block diagram of the device, and FIG. 4 is a timing chart showing an example of current during operation and during lock. 1 ... DC power supply, 2 ... Semiconductor commutator device, 3 ...
... DC motor without commutator, 6 ... Back electromotive force detection circuit, 7 ...
… Drive circuit, 11 …… Frequency detection circuit.

Claims (1)

[Claims] 1. An armature winding connected to a neutral point and not grounded, 6
A semiconductor commutator device formed by connecting three semiconductor switching elements in a three-phase bridge, a magnet rotor, and a counter electromotive voltage detection for detecting a relative position of the magnet rotor by a counter electromotive voltage generated in the armature winding. A circuit, a drive circuit for driving the semiconductor switching element of the semiconductor commutator device by the output of the counter electromotive voltage detection circuit, and the frequency of the output of the counter electromotive voltage detection circuit is detected and the detected frequency is operating normally. Of a DC motor without a commutator, which comprises a frequency detection circuit that determines that the motor is in a locked state when the frequency becomes higher than a set frequency higher than the maximum frequency and stops the operation of the drive circuit. Control device.