JPH09135591A - Overcurrent protector in brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a brushless motor from demagnetization, by preventing overcurrent and protecting semiconductor elements that control the brushless motor without using a base current changing means for the semiconductor elements. SOLUTION: A current carried at a brushless motor 1 is detected by a current detector 3 through a set of semiconductor elements 2. In a comparator 5, the current is compared with a reference voltage (Vref) generated from a reference value setter 4. According to the result, power to the semiconductor elements 2 is stopped after a first power stopping time (T1) by a control circuit 6 so that demagnetization caused by an overcurrent of the brushless motor 1 can be prevented surely. In addition, the power to the semiconductor elements is stopped by the control circuit 6 after a second power stopping time (T2), where T2>T1, so that the semiconductor elements can be protected surely from damage caused by an overcurrent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter operation of a compressor such as an air conditioner and a refrigerator, and more particularly to an overcurrent protection device for a brushless motor drive circuit.

[0002]

2. Description of the Related Art An overcurrent protection device for a brushless motor drive circuit is known from Japanese Utility Model Publication No. 218708. In the above publication, a plurality of reference values are provided for the current value of the brushless motor drive circuit, and the base currents of the semiconductor element groups are controlled so as to correspond to the reference values. However, in this case, means for varying the base current of the semiconductor element group is required, and the control circuit becomes complicated.

[0003]

In contrast to the problems in the prior art as described above, the present invention does not require a means for varying the base current of the semiconductor element group, and has a problem in the capacity and heat dissipation of the semiconductor element group. Without overcurrent, the semiconductor element group is protected and the demagnetization protection of the brushless motor is enabled.

[0004]

According to a first aspect of the present invention, there is provided an overcurrent protection device for a brushless motor, a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings for applying a rotating magnetic field to the rotor. A brushless motor configured by a wire, and a semiconductor element group for energizing the brushless motor,
A control circuit that controls the energization of the semiconductor element group, a current detector that detects the motor current, a reference value setter that sets a reference value that protects the motor overcurrent, and a current value detected by the current detector. In a brushless motor drive circuit having a comparator for comparing the reference value set by the reference value setting device,
Multiple different reference values are set by the reference value setter, the current value detected by the current detector and each reference value are compared by the comparator, and the energization of the semiconductor element group is stopped based on the comparison result. In the control circuit, the overcurrent protection process is performed by changing the predetermined time until the energization of the semiconductor element group is controlled according to the reference value.

In the brushless motor overcurrent protection device constructed as described above, it is possible to set an appropriate energization stop time of the semiconductor element group according to each overcurrent protection value, and the brushless motor against the overcurrent of the motor can be set. It enables the demagnetization protection and the overcurrent protection of the semiconductor element group.

An overcurrent protection device for a brushless motor according to a second aspect of the present invention comprises a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings that apply a rotating magnetic field to the rotor. Set a brushless motor, a semiconductor element group that energizes the brushless motor, a control circuit that controls energization of the semiconductor element group, a current detector that detects the motor current, and a reference value that protects the motor overcurrent. In a brushless motor drive circuit having a reference value setter and a comparator for comparing the current value detected by the current detector with the reference value set by the reference value setter, a plurality of different reference value setters are used. Set a reference value, compare the current value detected by the current detector with the comparator and each reference value, and perform overcurrent protection by the control circuit that controls the energization of the semiconductor element group based on the comparison result. place The method further includes a process of stopping the energization of the semiconductor element group within a predetermined time and a process of changing the energization rate of the semiconductor element group and continuing the energization. Set the overcurrent protection value for the demagnetization protection and the overcurrent protection of the semiconductor element group, and energize the semiconductor element group after a predetermined time according to the comparison result of the motor current and each overcurrent protection value. Overcurrent protection for stopping and overcurrent protection for continuing energization by changing the duty ratio of the semiconductor element group are performed.

In the brushless motor overcurrent protection device thus constructed, it is possible to set an appropriate energization state of the semiconductor element group in accordance with each overcurrent protection value.
The demagnetization protection of the brushless motor against the overcurrent of the motor and the overcurrent protection of the semiconductor element group are possible.

An overcurrent protection device for a brushless motor according to a third aspect of the present invention comprises a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings that apply a rotating magnetic field to the rotor. Set a brushless motor, a semiconductor element group that energizes the brushless motor, a control circuit that controls energization of the semiconductor element group, a current detector that detects the motor current, and a reference value that protects the motor overcurrent. In a brushless motor drive circuit that includes a reference value setter and a comparator that compares the current value detected by the current detector with the reference value set by the reference value setter, the current value detected by the current detector is Equipped with a signal converter that converts and outputs to multiple current detection signals, the reference value set by the reference value setting device and each signal output from the signal converter are compared by the comparator, and based on the comparison result In the control circuit for controlling the energization of the semiconductor element group, and performs change the predetermined time overcurrent protection process before stopping the energization of the semiconductor element groups in accordance with the reference value.

In the brushless motor overcurrent protection device constructed as described above, it is possible to set an appropriate energization stop time of the semiconductor element group according to each current detection signal. The demagnetization protection and the overcurrent protection of the semiconductor element group are possible.

An overcurrent protection device for a brushless motor according to a fourth aspect of the present invention comprises a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings that apply a rotating magnetic field to the rotor. Set a brushless motor, a semiconductor element group that energizes the brushless motor, a control circuit that controls energization of the semiconductor element group, a current detector that detects the motor current, and a reference value that protects the motor overcurrent. In a brushless motor drive circuit that includes a reference value setter and a comparator that compares the current value detected by the current detector with the reference value set by the reference value setter, the current value detected by the current detector is Equipped with a signal converter that converts and outputs to multiple current detection signals, the reference value set by the reference value setting device and each signal output from the signal converter are compared by the comparator, and based on the comparison result A control circuit for controlling the energization of the semiconductor element group performs an overcurrent protection process according to a reference value, a process of stopping energization of the semiconductor element group within a predetermined time, and a process of changing the energization rate of the semiconductor element group and continuing energization. Which includes a current conversion signal for converting a motor current into a current detection signal for demagnetization protection of a brushless motor and overcurrent protection of a semiconductor element group, and detecting each current detection signal and overcurrent protection. Depending on the result of comparison with the value, overcurrent protection for stopping energization of the semiconductor element group after a predetermined time and overcurrent protection for changing energization rate of the semiconductor element group to continue energization are performed.

In the overcurrent protection device for the brushless motor thus configured, it is possible to set an appropriate energization state of the semiconductor element group according to each current detection signal,
The demagnetization protection of the brushless motor against the overcurrent of the motor and the overcurrent protection of the semiconductor element group are possible.

An overcurrent protection device for a brushless motor according to a fifth aspect of the present invention comprises a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings that apply a rotating magnetic field to the rotor. Set a brushless motor, a semiconductor element group that energizes the brushless motor, a control circuit that controls energization of the semiconductor element group, a current detector that detects the motor current, and a reference value that protects the motor overcurrent. In a brushless motor drive circuit having a reference value setter and a comparator for comparing the current value detected by the current detector with the reference value set by the reference value setter, a plurality of different reference value setters are used. A reference value is set, the current value detected by the current detector is compared with the first reference value set by the reference value setting device, and a signal converter for converting to a pulse signal and outputting is provided, and is detected by the current detector. Electric current And a second reference value set by the reference value setting device are compared by a comparator, and based on the comparison result, the control circuit performs overcurrent protection processing for stopping energization of the semiconductor element group within a predetermined time. The control circuit measures the pulse signal output from the signal converter and performs an overcurrent protection process of stopping energization of the semiconductor element group after a predetermined number of times. Set the overcurrent protection value for the demagnetization protection and the overcurrent protection of the semiconductor element group, and according to the comparison result of the overcurrent protection value and the motor current set as the demagnetization protection of the brushless motor,
Overcurrent protection that stops the energization of the semiconductor element group after a predetermined time is performed, and the pulse signal of the motor current converted by the overcurrent protection value set as the overcurrent protection of the semiconductor element group and the motor current is measured and the predetermined number of times is measured. After reaching, overcurrent protection is performed to stop energization of the semiconductor element group.

In the brushless motor overcurrent protection device constructed as described above, it is possible to set an appropriate energization stop time of the semiconductor element group according to the motor current and its pulse signal, and the brushless motor against the overcurrent of the motor can be set. It enables the demagnetization protection and the overcurrent protection of the semiconductor element group.

An overcurrent protection device for a brushless motor according to a sixth aspect of the present invention comprises a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings that apply a rotating magnetic field to the rotor. Set a brushless motor, a semiconductor element group that energizes the brushless motor, a control circuit that controls energization of the semiconductor element group, a current detector that detects the motor current, and a reference value that protects the motor overcurrent. In a brushless motor drive circuit having a reference value setter and a comparator for comparing the current value detected by the current detector with the reference value set by the reference value setter, a plurality of different reference value setters are used. Set the reference value, compare the current value detected by the current detector with the first reference value set by the reference value setting device, convert it into a pulse signal and output it. value The second overcurrent protection value set by the reference value setter is compared by the comparator, and based on the comparison result, the control circuit performs the overcurrent protection process of stopping the energization of the semiconductor element group within a predetermined time. Along with, it is characterized in that the control circuit measures the pulse signal output from the signal converter, and after a predetermined number of times, performs the overcurrent protection process of continuing the energization by changing the duty ratio of the semiconductor element group, Set the overcurrent protection value for the demagnetization protection of the brushless motor and the overcurrent protection of the semiconductor element group against the motor current, and compare the overcurrent protection value set as the demagnetization protection of the brushless motor with the motor current. According to the above, overcurrent protection is performed to stop the energization of the semiconductor element group after a predetermined time, and at the same time, the overcurrent protection value set for overcurrent protection of the semiconductor element group and the motor current converted by the motor current are After a predetermined number of times reaches to measure the scan signals, in which by changing the energization of the semiconductor element groups perform overcurrent protection to continue energization.

In the brushless motor overcurrent protection device constructed as described above, it is possible to set an appropriate energization state of the semiconductor element group in accordance with the motor current and the pulse signal thereof, and the brushless motor against the overcurrent of the motor can be set. The demagnetization protection and the overcurrent protection of the semiconductor element group are possible.

[0016]

1 is a block diagram of an embodiment of the present invention. In FIG. 1, 1 is a brushless motor, 2 is a semiconductor element group, 3 is a current detector, 4 is a reference value setter, 5
Is a comparator, 6 is a control circuit, and 7 is a signal converter. The current detector 3 detects the motor current flowing through the brushless motor 1 via the semiconductor element group 2. Reference value setter 4
In the above, the first reference value Vref1 is set as the demagnetization protection of the brushless motor 1, and in the comparator 5, the reference value Vref1 is set.
The signal detected by the ref1 and the current detector 3 is converted into the signal converter 7
The motor current converted in step S1 is compared, and the control circuit 6 stops energization of the semiconductor element group 2 after the first energization stop time T1 determined by the first reference value Vref1 based on the comparison result. Demagnetization due to overcurrent is surely protected.

Further, the reference value setter 4 sets a second reference value Vref2 such that Vref2 <Vref1 as overcurrent protection of the semiconductor element group 2, and the control circuit 6 sets T
After the second energization stop time T2 of 2> T1, the energization of the semiconductor element group 2 is stopped. By setting the reference values so that the respective values are different from each other by the required number, it is possible to selectively adjust the time during which the energization of the semiconductor element group 2 is stopped. In this way, destruction of the semiconductor element group due to overcurrent is reliably protected.

FIG. 2 shows a block diagram of an embodiment in the case where the energization stopping process and the energization rate changing process of the semiconductor element group are performed in the control circuit. In FIG. 2, the same parts as those shown in FIG. 1 are designated by the same reference numerals. In the reference value setter 4, as the demagnetization protection of the brushless motor 1, a first reference value Vref1 that serves as a reference for stopping energization is set, and in the comparator 5, the reference value Vref1 and the current detected by the current detector 3 are set. The motor current converted by the signal converter 7 is compared, and based on the comparison result, the control circuit 6 stops energizing the semiconductor element group 2 after a predetermined time.
Demagnetization due to overcurrent is surely protected.

The reference value setter 4 sets a second reference value Vref2 such that Vref2 <Vref1 as overcurrent protection of the semiconductor element group 2, and the control circuit 6 sets the reference value Vref2 based on the result of comparison with the motor current. The energization of the semiconductor element group 2 is reduced by the energization rate D1 to continue the operation. The reference values are provided so as to differ from each other by the required number, so that the duty factor of the semiconductor element group 2 is reduced according to each reference value and the operation is continued. In this way, destruction due to overcurrent is surely protected without stopping energization of the semiconductor element group.

FIG. 3 shows a block diagram of an embodiment in which the overcurrent protection process is performed after converting the detected current into a plurality of current signals. In FIG. 3, the same parts as those shown in FIG. 1 are designated by the same reference numerals. The signal converter 7 converts the current detected by the current detector 3 with the minimum integration time constant K1 and the minimum conversion gain G1 to obtain the maximum integration time constant KN and the minimum current time from the first current signal. Is converted into the Nth current signal obtained by the conversion gain GN.

As shown in FIG. 4, the converted current signal corresponds to the detected current 8 of the current detector 3 according to the combination of the integration time constant and the conversion gain, and the curves 9, 10, 11 respectively. As in the overcurrent protection value, the crossing points with respect to a certain threshold are different. The first current signal obtained by converting the current detected by the current detector 3 by the minimum integration time constant K1 and the minimum conversion gain G1 in the signal converter 7 and the reference value Vref set in the reference value setting unit 4 Based on the comparison result in the comparator 5, the control circuit 6 stops the energization of the semiconductor element group 2 after the first energization stop time T1.
Demagnetization due to overcurrent of the brushless motor 1 is surely protected.

Further, in the signal converter 7, an integration time constant K2 that satisfies K2> K1 and a conversion gain G that satisfies G2> G1.
Based on the comparison result of the second current signal converted by 2 and the reference value Vref set by the reference value setting device 4,
Second energization stop time T such that T2> T1 in the control circuit
After 2, the power supply to the semiconductor element group 2 is stopped and the semiconductor element group 2
Reliably protects against damage due to overcurrent.

As a modified example of this embodiment, in the control circuit 6, the energization of the semiconductor element group 2 is stopped after the first energization stop time T1, and the demagnetization due to the overcurrent of the brushless motor 1 is surely protected. After the time T2, the control circuit 6 may be configured to continue the operation by reducing the energization rate of the semiconductor element group 2 by the energization rate D1. As described above, the conversion constants of the signal converter 7 are made different and selectively provided, so that the energization stop time or the energization rate change time of the semiconductor element group 2 can be changed according to each current signal.

In FIG. 4, the current signal 9 obtained by converting the detected current 8 and the overcurrent protection value are compared, and the energization of the semiconductor element group is stopped after the energization stop time T1 after the current signal exceeds the overcurrent protection value. Here is an example. The energization stop time T2 and TN are
It shows the time from when the current signal 10 and the current signal 11 exceed the overcurrent protection value to when the energization is stopped.

FIG. 5 shows a block diagram of an embodiment in which the overcurrent protection process by the detected current and the reference value and the overcurrent protection process after converting the detected current into a pulse signal are performed. 5, the same components as those shown in FIG. 1 are designated by the same reference numerals, and 12 is a signal converter. The reference value setter 4 sets a first reference value Vref1 as demagnetization protection for the brushless motor 1, and the control circuit 6 sets a first reference value Vref1 based on the comparison result between the reference value Vref1 and the current detected by the current detector 3. The semiconductor element group 2 after the energization stop time T1 of 1
To stop demagnetization due to overcurrent of the brushless motor 1 without fail.

Further, the reference value setting device 4 sets a second reference value Vref2 satisfying Vref2 <Vref1 as overcurrent protection of the semiconductor element group 2, and the signal converter 12 detects the reference value Vref2 and the current detector 3. After the detected currents match with each other, the detected current is converted into a pulse signal, the number of pulses of the pulse signal is measured in the control circuit 6, and when a predetermined number of times is reached, the second energization stop time T becomes T2> T1.
After 2, the power supply to the semiconductor element group 2 is stopped and the semiconductor element group 2
Reliably protects against damage due to overcurrent.

In FIG. 6, the detected current 13 of the current detector 3 and the reference value Vref1 of the reference value setting device 4 are compared by the comparator 5,
An example is shown in which the energization of the semiconductor element group is stopped after the energization stop time T1 after the current exceeds the reference value. The energization stop time T2 indicates the time until the pulse signal 14 reaches a predetermined number of times and the energization is stopped.

As a modified example of this embodiment, in the control circuit 6, the energization of the semiconductor element group 2 is stopped after the first energization stop time T1, and the demagnetization due to the overcurrent of the brushless motor 1 is surely protected. After the time T2, the control circuit 6 may be configured to continue the operation by reducing the energization rate of the semiconductor element group 2 by the energization rate D1.

In each embodiment, the reference value is set as the overload protection of the semiconductor element group, and the energization stop time of the semiconductor element group is set longer than the energization stop time for the overcurrent protection of the semiconductor element group. Alternatively, the overload operation of the semiconductor element group may be protected. Further, the reference value set as the demagnetization protection of the brushless motor may be set as the overcurrent protection of the semiconductor element group. Furthermore, as the overcurrent protection process, each process of stopping energization and changing the energization ratio may be combined other than those shown in the embodiments. In the present invention, the reference value setting device, the signal converter, the comparator, and the control circuit are not limited to hardware configurations, and may be software configurations or a combination of hardware and software.

[0030]

As described above, in the overcurrent protection device for a brushless motor of the present invention, it is possible to set an appropriate energization stop time or energization state of the semiconductor element group according to each overcurrent protection value. The demagnetization protection of the brushless motor against the overcurrent of the motor and the overcurrent protection of the semiconductor element group are possible. In addition, it is possible to set an appropriate energization state such as energization stop time or energization rate change of the semiconductor element group according to each current detection signal, and to demagnetize the brushless motor against overcurrent of the motor and to protect the semiconductor element group. Overcurrent protection.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a block diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing operating characteristics of the embodiment of FIG.

FIG. 5 is a block diagram showing another embodiment of the present invention.

6 is a diagram showing operating characteristics of the embodiment of FIG.

[Explanation of symbols]

 1 ・ ・ ・ Brushless motor 2 ・ ・ ・ Semiconductor element group 3 ・ ・ ・ Current detector 4 ・ ・ ・ Reference value setting device 5 ・ ・ ・ Comparator 6 ・ ・ ・ Control circuit 7, 12 ・ ・ ・ Signal converter 8 , 13, ・ ・ ・ Detected current 9, 10, 11, 14, ・ ・ ・ Detected current conversion result

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideaki Kato 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (6)

[Claims] 1. A brushless motor including a rotor having permanent magnets having a plurality of poles, a plurality of stator windings for applying a rotating magnetic field to the rotor, and a semiconductor element group for energizing the brushless motor. A control circuit for controlling energization of the semiconductor element group, a current detector for detecting a motor current,
Brushless motor drive equipped with a reference value setter that sets a reference value that protects the motor overcurrent, and a comparator that compares the current value detected by the current detector with the reference value set by the reference value setter In the circuit, a plurality of different reference values are set by the reference value setting device, the current value detected by the current detector and each reference value are compared by the comparator, and the semiconductor element group of the semiconductor element group is based on the comparison result. An overcurrent protection device for a brushless motor, wherein an overcurrent protection process is performed by changing a predetermined time until the energization of a semiconductor element group is stopped according to a reference value in a control circuit for controlling energization. 2. A reference value setting device sets a plurality of different reference values, a comparator compares the current value detected by a current detector with each reference value, and the semiconductor device is based on the comparison result. The overcurrent protection process performed by the control circuit for controlling energization of the group includes a process of stopping energization of the semiconductor element group within a predetermined time and a process of changing the energization rate of the semiconductor element group and continuing energization. An overcurrent protection device for a brushless motor according to claim 1. 3. A signal converter for converting a current value detected by a current detector into a plurality of current detection signals and outputting the plurality of current detection signals, wherein the reference value set by the reference value setting device and each signal output from the signal converter. And a comparator, and the control circuit that controls the energization of the semiconductor element group based on the comparison result changes the predetermined time until the energization of the semiconductor element group is stopped according to the reference value. The overcurrent protection device for a brushless motor according to claim 1, wherein a protection process is performed. 4. A signal converter that converts a current value detected by a current detector into a plurality of current detection signals and outputs the plurality of current detection signals. The reference value set by the reference value setting device and each signal output from the signal converter. Comparing with a comparator, the control circuit for controlling the energization of the semiconductor element group based on the comparison result performs the overcurrent protection processing according to the reference value and the processing of stopping the energization of the semiconductor element group within a predetermined time. The overcurrent protection device for a brushless motor according to claim 1, further comprising: a process of changing a duty ratio of the semiconductor element group and continuing energization. 5. A plurality of different reference values are set by the reference value setting device, and the current value detected by the current detector and the first reference value set by the reference value setting device are compared and converted into a pulse signal. A semiconductor device group is provided with a signal converter for outputting, the current value detected by the current detector and the second reference value set by the reference value setting device are compared by a comparator, and the control circuit is based on the comparison result. Performs overcurrent protection processing to stop energization of within a predetermined time, and also performs overcurrent protection processing to stop energization of the semiconductor element group after a predetermined number of times by measuring the pulse signal output from the signal converter in the control circuit The overcurrent protection device for a brushless motor according to claim 1, wherein: 6. The reference value setting device sets a plurality of different reference values, and the current value detected by the current detector and the first reference value set by the reference value setting device are compared and converted into a pulse signal and output. And a signal converter for controlling the current value detected by the current detector and the second overcurrent protection value set by the reference value setting device by the comparator, and based on the comparison result, the semiconductor device by the control circuit. Performs overcurrent protection processing to stop energization of the group within a predetermined time, measures the pulse signal output from the signal converter in the control circuit, and after a predetermined number of times changes the energization rate of the semiconductor element group and continues energization The overcurrent protection device for a brushless motor according to claim 1, wherein an overcurrent protection process is performed.