TWI398657B - Method for detecting open-circuit and short-circuit failures of motor coils - Google Patents

Description

Motor winding open circuit and short circuit fault detection method

The present invention relates to electric motors, and more particularly to the detection of faults in brushless DC motors (BLDC).

Electric motors are undoubtedly a very basic and important equipment in the industrial society, with an annual market demand of more than 5 billion units. Among the wide variety of motors, brushless DC motors (BLDC) are often used in hard disk drives and many other industrial applications, such as automotive parts and home appliances.

A typical brushless DC motor consists of a multi-phase winding rotor with a ring on the outside and a permanent magnet rotor on the inside. There is an air gap between the two, and the rotation of the rotor generates a magnetic flux in the air gap. Therefore, a back electromotive force (back-EMF) is generated, which is induced by the rotation of the permanent magnet rotor in front of the winding stator, and is independent of the energy of the input motor, which is proportional to the motor Speed, rotor flux and the number of turns of the corresponding winding.

The motor controller usually contains a high-power field effect transistor (FET), which is easily burned by overheating or overcurrent. It is difficult to detect the fault inside the motor before passing through the motor controller before the motor fault is found. Powering the motor will cause serious damage to the motor controller.

SUMMARY OF THE INVENTION A primary object of the present invention is to provide a motor winding open circuit and short circuit detection method that can be tested using a commercially available motor controller without the need to purchase additional equipment and additional expense, which is extremely economical, simple, and effective.

The first figure shows a typical application circuit diagram of a commercially available sensorless brushless DC motor controller and a brushless DC motor. The three-phase windings 304, 305, and 306 of the brushless motor 300 are respectively via three terminals 301, 302, 303. And connected to the three-phase driving circuit 210, 220, 230, the three-phase windings 304, 305, 306 shown in the figure are Y-connected type, of course, can also be Δ-connected. The three-phase driving circuit 210, 220, 230 includes three pairs (ie, six) of electronic switches 211, 212, 221, 222, 231, 232 formed by field effect transistors, wherein the electronic switches 211 and 212 are the first pair, and the electronic switches 221 and 222 are the second pair, the electronic switch 231 and 232 are the third pair, each pair consists of a P-channel high side switch 211, 221, 231 and an N-channel low side switch 212, 222, 232. Although the illustrated electronic switches 211, 212, 221, 222, 231, 232 are field effect transistors, It can be other switching components, such as an isolated gate dual carrier transistor (IGBT) or a bipolar junction transistor (BJT). The source (ie, the power supply terminal) of each high side switch 211, 221, 231 is connected in parallel to the current. The constant voltage source Vp, the gates (ie, the gate terminals) of all the electronic switches 211, 212, 221, 222, 231, 232 are respectively connected to a microcontroller 100, and the voltage levels of the three-phase windings 304, 305, 306 are fed back to the microcontroller via the voltage dividing circuits 410, 420, 430. An analog to digital converter (ADC) input, i.e., winding feedback inputs 101-103, maintains the feedback voltage within an acceptable range for the microcontroller 100. Another component voltage circuit 440 is suitable for some special motor controllers, as a virtual ground reference point, and its voltage dividing point is connected to the fourth ADC input terminal 104 of the microcontroller 100, that is, the virtual ground feedback input.

The second figure is shown as an open circuit detection process performed by the microcontroller 100, first turning off all of the electronic switches 211, 212, 221, 222, 231, 232 (step 501), and then turning on any of the high side switches 211, 221, 231 (step 502), such as the first high side switch. 211, the power supply voltage Vp is applied to all the windings, and then the voltage value of the three-winding feedback input terminals 101-103 is read (step 503), and the voltage value is judged whether the winding is an open circuit (step 504). All voltage values are higher than a reference value, that is, no open circuit fault condition (step 506), the reference value can be preferably selected as 50% of the Vp value, but if a voltage value is lower than the reference value, the winding is indicated There is an open circuit failure condition (step 505).

The third figure shows the winding-to-winding or winding-to-supply (including live and ground) short-circuit detection process performed by the microcontroller 100. First, all electronic switches 211, 212, 221, 222, 231, 232 are turned off for a first time, for example, 50 micro. Seconds (step 511) to eliminate the residual voltage, and then turn on a high side switch 211, 221, 231 and a different pair of low side switches 212, 222, 232, such as the first high side switch 211 and the second low side switch 222, for a short period of time After the second time of the first time, it is turned off, for example, 5 microseconds, so that a short pulse current flows through the two windings connected to the two opened electronic switches (such as 211 and 222), such as the first winding 304 and The second winding 305 (step 512), then turns off the previously turned on electronic switches (such as 211 and 222) (step 513), and then simultaneously records the winding feedback inputs (such as 102 and 101) connected to the two electronic switches ( Step 514). If there is no short circuit condition between the two windings, a back electromotive force is generated on the winding after the current is stopped, and the back electromotive force is expressed in the voltage between the first and second terminals 301, 302, which can be recorded simultaneously by The windings connected to the two tested windings are fed back to the voltage values of the input terminals 101, 102 and are measured. Following the foregoing step 514, calculating a difference between the voltage values of the feedback terminals of the two tested windings (step 515), and comparing the difference with a threshold value (step 516), if the difference is greater than the threshold value, It means that there is no short circuit fault between the two tested windings (such as 304 and 305); conversely, if the difference is less than the critical value, it means that there is a short circuit fault between the two tested windings. Repeatedly in the above method, the combination of the other high-side high-off 211, 221, 231 and the low-side switches 212, 222, 232, taking the three-phase winding as an example, the combination of any two windings has only three possibilities, so only three different high-side switches and low are tested. The side switch combination completes the short circuit detection of all windings to the windings. The short-circuit detection method described above can not only detect the short-circuit fault of the winding to the winding, but also detect the short-circuit fault between the winding and the power supply line or ground.

The fourth figure is the voltage waveform between the two tested terminals in the short circuit detecting method of the present invention in the absence of a short circuit fault condition, the waveforms 602 and 603 are waveforms of the winding feedback input terminals 102 and 101, respectively, and the section 600 is an electronic switch. During the on period (ie, the aforementioned second time), the segment 601 represents the voltage change recorded by the two-winding feedback input terminal 101, 102 after the electronic switch is again turned off (ie, after the second time has elapsed), and the waveform 605 is taken as the waveform 602. The difference obtained after subtracting the waveform 603, the dashed line 604 represents the aforementioned critical value, and the difference is higher than the critical value to reflect the existence of a counter electromotive force. Conversely, the fifth figure shows the state in the case of a short-circuit fault, the waveforms 612 and 613 are also the waveforms of the input terminals 102 and 101, respectively, and the waveform 615 represents the difference between the two, and it can be seen that the difference is Both are below the critical value, which means that there is no counter electromotive force.

The method of the present invention is implemented by a commercially available microcontroller, but not every commercially available microcontroller has the ability to simultaneously record two sets of ADC input values, if the microcontroller used does not have two sets of simultaneous recordings. The ability of the data, that is, the above method must be slightly changed, that is, segmented records. Referring to the sixth figure, steps 531-533 are the same as the foregoing steps 511-513, but step 534 is changed to record only the voltage value of the single winding feedback input (for example, 102), and this recording operation continues for a third time. For example, the same 50 microseconds as the first time, and then steps 532 and 533, ie, steps 535 and 536 are performed again, but step 537 is changed to record only the voltage value of another single winding feedback input (eg, 101). The action is recorded and continues for the third time, and finally steps 515-518, steps 538-541, are performed. This method achieves the same short-circuit detection effect as the aforementioned simultaneous recording in two recordings, but the principle is completely the same.

The seventh figure shows another short-circuit detection method of the winding-to-winding of the present invention. The voltage ground reference point and the voltage of a winding terminal are used as a comparison basis, and all the steps are substantially the same as those shown in the third figure. Only at step 564 of step 514 of the third figure, a winding feedback input terminal (such as 102) and a virtual ground feedback input terminal 104 connected to the measured winding are simultaneously recorded, and step 565 is correspondingly calculated to calculate the winding input. The difference between the terminal voltage value and the voltage value of the virtual ground feedback input terminal is finally compared with the difference value to determine whether there is a short circuit fault. Of course, the aforementioned virtual ground short-circuit detection method can also adopt the method of recording the two-stage recording voltage value as shown in the sixth figure, that is, as shown in the eighth figure, the two are substantially the same, and the difference is only that one winding is fed back. The end is changed to the virtual ground feedback input 104.

The ninth figure shows the voltage waveform between the two tested terminals in the absence of a short-circuit fault in the above-described virtual ground short-circuit detecting method of the present invention, waveforms 622 and 623 are waveforms of the input terminals 102 and 104, respectively, and section 620 represents an electronic switch. During the on period (ie, the second time), the segment 621 represents the voltage change recorded by the two inputs 104, 102 after the electronic switch is turned off again (ie, after the second time), and the waveform 625 is subtracted from the waveform 622. The difference obtained after the waveform 623, the broken line 624 indicates the aforementioned critical value, and the difference is higher than the critical value to reflect the existence of a counter electromotive force. Conversely, the tenth figure shows the state when there is a short circuit fault, and the waveforms 632 and 633 are also the waveforms of the winding feedback input terminal 102 and the virtual ground feedback input terminal 104, respectively, and the waveform 635 represents the difference between the two. It can be seen that the difference is lower than the critical value, which means that there is no counter electromotive force.

100. . . Microcontroller

101-103. . . Winding feedback input

104. . . Virtual ground feedback input

210,220,230. . . Drive circuit

211,212,221,222,231,232. . . electronic switch

300. . . Brushless motor

301,302,303. . . Terminal

304,305,306. . . Winding

410,420,430,440. . . Voltage dividing circuit

501-506, 511-518. . . step

The first picture is a circuit diagram of a brushless DC motor and a non-inductive brushless motor controller.

The second figure is a flow chart of the method for detecting the open circuit of the motor winding of the present invention.

The third figure is a flow chart of the motor winding short-circuit detecting method of the present invention simultaneously recording two sets of feedback value modes.

The fourth figure is a waveform diagram of the third figure in the absence of a short circuit.

The fifth figure is a waveform diagram of the third figure in the short circuit state.

The sixth figure is a flow chart of the motor winding short-circuit detecting method of the present invention in the mode of recording the two sets of feedback values.

The seventh figure is a flow chart of the motor winding short-circuit detecting method of the present invention adopting a virtual ground feedback input and simultaneously recording two sets of feedback value modes.

The eighth figure is a flow chart of the motor winding short-circuit detecting method of the present invention using virtual ground feedback input and fractional recording in two sets of feedback value modes.

The ninth diagram is a waveform diagram of the seventh diagram in the absence of a short circuit.

The tenth figure is a waveform diagram of the seventh figure in the short circuit state.

501-506, 511-518. . . step

Claims (16)

A motor winding open circuit detecting method is a brushless DC motor having a multi-phase stator winding, wherein the windings are respectively connected to a multi-phase driving circuit via a terminal, and each phase driving circuit is composed of a pair of electronic switches. Each pair of electronic open relationship is composed of a high side switch and a low side switch, and the power end of each high side switch is connected in parallel to the constant current voltage source Vp, and the gate terminals of all the electronic switches are respectively connected to one The microcontroller, the voltage level of each winding is fed back to the analog of the microcontroller to the digital converter (ADC) input, that is, the winding feedback input, the open circuit detection method includes the following steps: a) cutting off all electrons Switching; b) conducting a single high-side switch to apply a supply voltage Vp to all windings; c) reading the voltage value of all winding feedback inputs; d) judging by the voltage value read in step c) Whether the winding is open circuit, if all the voltage values are higher than a reference value, it is no open circuit fault condition; if a voltage value is lower than the reference value, it means that the winding has an open circuit fault condition. The motor winding open circuit detecting method according to claim 1, wherein the reference value is 50% of a Vp value. A motor winding short-circuit detecting method is a brushless DC motor having a multi-phase stator winding, wherein the windings are respectively connected to a multi-phase driving circuit via a terminal, and each phase driving circuit is composed of a pair of electronic switches. Each pair of electronic open relationship is composed of a high side switch and a low side switch, and the power end of each high side switch is connected in parallel to the constant current voltage source Vp, and the gate terminals of all the electronic switches are respectively connected to one The microcontroller, the voltage level of each winding is fed back to the analog of the microcontroller to the input of the digital converter (ADC), that is, the winding feedback input, the short circuit detection method comprises the following steps: a) cutting off all electrons Switching for a first time; b) turning on a high side switch and a pair of low side switches, and continuing for a short time after the second time of the first time to make a short pulse current Flowing through the winding connected to the two opened electronic switches; c) cutting off the previously turned on electronic switch; d) simultaneously recording the voltage value of the winding feedback input connected to the two electronic switches; e) The difference between the voltage values of the two winding feedback input terminals; f) comparing the difference value with a threshold value to determine whether there is a short circuit fault between the two tested windings, and if the difference is greater than the critical value, the There is no short circuit fault between the two tested windings; if the difference is less than the critical value, it means that there is a short circuit fault between the two windings. The motor winding short-circuit detecting method according to claim 3, wherein the first time is 50 microseconds. The motor winding short-circuit detecting method according to claim 4, wherein the second time is 5 microseconds. A motor winding short-circuit detecting method is a brushless DC motor having a multi-phase stator winding, wherein the windings are respectively connected to a multi-phase driving circuit via a terminal, and each phase driving circuit is composed of a pair of electronic switches. Each pair of electronic open relationship is composed of a high side switch and a low side switch, and the power end of each high side switch is connected in parallel to the constant current voltage source Vp, and the gate terminals of all the electronic switches are respectively connected. To a microcontroller, the voltage level of each winding is fed back to the analog input of the microcontroller to the input of the digital converter (ADC), that is, the winding feedback input. The short circuit detection method includes the following steps: a) cutoff All electronic switches continue for a first time; b) conduct a high side switch and a low side switch of a different pair thereof, and continue to be short after a second time of the first time to make a short a pulse current flowing through the winding connected to the two opened electronic switches; c) cutting off the previously turned on electronic switch; d) recording the voltage value of any of the winding feedback inputs connected to the two electronic switches, and continuing the first Three times; e) repeat steps b) to c); f) record another voltage value of the winding feedback input connected to the two electronic switches, and continue the third time; g) calculate the two winding feedback input The difference between the voltage values; h) comparing the difference with a threshold value to determine whether there is a short circuit fault between the two tested windings, and if the difference is greater than the critical value, it means that there is no between the two tested windings Short circuit fault; if the difference is less than The critical value indicates that there is a short circuit fault between the two windings. The motor winding short-circuit detecting method according to claim 6, wherein the first time is 50 microseconds. The motor winding short-circuit detecting method according to claim 7, wherein the second time is 5 microseconds. The motor winding short-circuit detecting method according to claim 7, wherein the third time is 50 microseconds. A motor winding short-circuit detecting method is a brushless DC motor having a multi-phase stator winding, wherein the windings are respectively connected to a multi-phase driving circuit via a terminal, and each phase driving circuit is composed of a pair of electronic switches. Each pair of electronic open relationship is composed of a high side switch and a low side switch, and the power end of each high side switch is connected in parallel to the constant current voltage source Vp, and the gate terminals of all the electronic switches are respectively connected to one The microcontroller, the voltage level of each winding is fed back to the analog of the microcontroller to the input of the digital converter (ADC), that is, the winding feedback input, and another virtual ground reference point is connected to the other of the microcontroller The ADC input, the virtual ground feedback input, includes the following steps: a) turning off all electronic switches for a first time; b) turning on a high side switch and a low side of a different pair Switching, and continuing for a second time after the second time, to turn off a short pulse current through the winding connected to the two opened electronic switches; c) cutting off the aforementioned conductive The electronic switch; d) simultaneously recording the voltage value of any one of the winding feedback input terminal and the virtual ground feedback input terminal connected to the two electronic switches; e) calculating the voltage value of the winding feedback input terminal and the voltage value of the virtual ground feedback input terminal Difference; f) comparing the difference with a threshold value to determine whether there is a short circuit fault between the two tested windings, and if the difference is greater than the threshold value, it means that there is no short circuit fault between the two tested windings; If the difference is less than the threshold, it means that there is a short circuit fault between the two windings. The motor winding short-circuit detecting method according to claim 10, wherein the first time is 50 microseconds. The motor winding short-circuit detecting method according to claim 11, wherein the second time is 5 microseconds. A motor winding short-circuit detecting method is a brushless DC motor having a multi-phase stator winding, wherein the windings are respectively connected to a multi-phase driving circuit via a terminal, and each phase driving circuit is composed of a pair of electronic switches. Each pair of electronic open relationship is composed of a high side switch and a low side switch, and the power end of each high side switch is connected in parallel to the constant current voltage source Vp, and the gate terminals of all the electronic switches are respectively connected to one The microcontroller, the voltage level of each winding is fed back to the analog of the microcontroller to the input of the digital converter (ADC), that is, the winding feedback input, and another virtual ground reference point is connected to the other of the microcontroller The ADC input, the virtual ground feedback input, includes the following steps: a) turning off all electronic switches for a first time; b) turning on a high side switch and a low side of a different pair Switching, and continuing for a second time after the second time, to turn off a short pulse current through the winding connected to the two opened electronic switches; c) cutting off the aforementioned conductive Electronic switch; d) recording the voltage value of any of the winding feedback inputs connected to the two electronic switches for a third time; e) repeating steps b) to c); f) recording the virtual ground feedback input The voltage value continues for the third time; g) calculating the difference between the voltage value of the feedback input end of the winding and the voltage value of the virtual ground return input terminal; h) comparing the difference value with a threshold value to determine whether there is a short circuit fault between the two tested windings, The difference is greater than the critical value, that is, there is no short circuit fault between the two tested windings; if the difference is less than the critical value, it means that there is a short circuit fault between the two windings. The motor winding short-circuit detecting method according to claim 13, wherein the first time is 50 microseconds. The motor winding short-circuit detecting method according to claim 14, wherein the second time is 5 microseconds. The motor winding short-circuit detecting method according to claim 14, wherein the third time is 50 microseconds.