A detection method for star contactors of elevators based on frequency converter control permanent magnet synchronous motors

Abstract

The present invention discloses a method for detecting a sealing contactor for elevators, comprising the following steps: Step 1: When there is no output contactor, keep the PM motor stopped and the main contacts of the sealing contactor closed, proceed to Step 2; When there is an output contactor, close the output contactor to keep the PM motor stopped and the main contacts of the sealing contactor closed, proceed to Step 2; Step 2: Any two or three phases of the U-phase, V-phase, and W-phase of the frequency converter output a small voltage, proceed to Step 3; Step 3: Perform sealing function detection based on phase current related information. The present invention also discloses a method for detecting a sealing contactor for elevators with an output contactor. The present invention can detect whether the sealing contactor for elevators is in an effective state without releasing the brake, posing no safety risk.

Description

Technical Field

[0001] This invention relates to the field of elevator sealing contactor testing technology, and in particular to a method for testing elevator sealing contactors based on a frequency converter-controlled permanent magnet synchronous motor. Background Technology

[0002] With the development of elevator technology, the safety requirements for elevators are becoming increasingly stringent. To ensure that the elevator can effectively slow down or limit its speed, a common practice is to short-circuit the three-phase input of the traction motor (permanent magnet synchronous motor). The braking force generated by the permanent magnets of the permanent magnet synchronous motor (PM motor) is then used to slow down or limit the elevator's speed (i.e., "star-sealing technology"). See also... Figure 1 Currently, the commonly used method for sealing off elevator control systems is to use a "sealing off contactor". A sealing off contactor is added between the frequency converter and the PM motor to achieve short-circuiting of the three-phase input of the PM motor.

[0003] Typically, the star-sealing function of an elevator control system is tested primarily through the auxiliary contacts of the star-sealing contactor. However, when testing the star-sealing function solely through the auxiliary contacts, if the star-sealing contactor is damaged and not replaced for various reasons, or if the wiring is altered and the operating signals of other contactors are connected to the star-sealing function testing port, then that monitoring point is not actually detecting the operation of the star-sealing contactor. Alternatively, if the U-phase, V-phase, W-phase, or jumper wire connected to the main contacts of the star-sealing contactor is removed or the wiring is interrupted, although the contactor may operate, the actual star-sealing function is not present.

[0004] The elevator sealing contactor detection method and device disclosed in Chinese invention patent application publication number CN114415007A proposes to release the brake (i.e., open the brake) when the elevator stops, allowing the elevator to roll back. Whether the speed or acceleration exceeds a preset value within a preset time is used to determine whether the sealing function is qualified. However, this method requires releasing the brake (i.e., opening the brake), which poses a certain risk. It also requires determining whether there are people in the car, and obtaining the preset time and preset speed is relatively complex.

[0005] Furthermore, Chinese invention patent application publication number CN114715749A discloses an automatic detection method, system, device, and storage medium for elevator star-sealing function. This method is applied to the elevator control system. When a star-sealing function detection command is detected, it acquires the elevator's target service floor information. After controlling the elevator car to run to the target floor corresponding to the target service floor information, it activates the star-sealing module to allow the elevator car to enter a gliding state. It acquires the gliding speed or gliding distance of the elevator car in this gliding state and determines whether the elevator star-sealing function meets preset requirements based on the gliding speed or gliding distance. This method also requires releasing the brake (i.e., opening the holding brake), which carries certain risks. It also requires running to a specific floor. Additionally, because the output contactor needs to be closed during gliding, it cannot determine whether the star-sealing contactor is connected to the front end of the output contactor, thus causing the star-sealing function to fail.

[0006] Chinese invention patent application publication number CN115009949A discloses a method for detecting the sealing status of an elevator. This method includes: ① the detection unit detecting the power supply status of the power supply circuit; ② when the power supply circuit switches from energized to de-energized, the main controller controls the detection switch to close, inputting low-voltage variable frequency AC power to the sealing circuit, and detecting the current value I in the detection switch circuit; ③ when the current value I in the circuit is less than or equal to a threshold Y, the main controller determines that the sealing circuit is open-circuited, thereby determining that the sealing module is abnormal and sending a fault signal to the control system, which then prohibits the elevator from operating; when the current value I in the circuit is greater than the threshold Y, the main controller determines that the sealing circuit is closed and that the sealing circuit is normal. This elevator sealing status detection method can detect whether the sealing module is working properly, ensuring the safety of elevator use and improving the elevator's safety level. However, this method requires additional hardware circuitry, increasing costs. Summary of the Invention

[0007] One of the objectives of this invention is to address the shortcomings of existing elevator sealing contactor detection methods that require releasing the brake (i.e., opening the brake), and to provide an elevator sealing contactor detection method based on a frequency converter-controlled permanent magnet synchronous motor that does not require releasing the brake.

[0008] The second objective of this invention is to address the problem that existing elevator sealing contactor detection methods cannot detect whether the sealing contactor is connected to the front or back end of the output contactor, and to provide an elevator sealing contactor detection method based on a frequency converter-controlled permanent magnet synchronous motor.

[0009] The third objective of this invention is to address the shortcomings of existing elevator sealing contactor detection methods that use a slip-out method and require the output contactor to be closed before the brake can be released, which makes it impossible to determine whether the sealing contactor is connected to the front end of the output contactor, thus causing the sealing function to fail. Therefore, this invention provides an elevator sealing contactor detection method based on a frequency converter-controlled permanent magnet synchronous motor.

[0010] To achieve one of the above-mentioned objectives, the elevator sealing contactor detection method based on a frequency converter-controlled permanent magnet synchronous motor of the present invention may include the following steps:

[0011] Step 1: When there is no output contactor, keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 2; when there is an output contactor, close the output contactor to keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 2.

[0012] Step 2: Output a small voltage from any two or three phases of the inverter's U-phase, V-phase, and W-phase, then proceed to Step 3;

[0013] Step 3: Perform a star-sealing function test based on the information related to the first phase current.

[0014] In a preferred embodiment of the present invention, in step two, if any two of the U-phase, V-phase, and W-phase of the frequency converter output a small voltage, then steps two and three need to be repeated twice, and any two phases in the two repetitions are different.

[0015] In a preferred embodiment of the present invention, step three, which involves detecting the sealing function based on the information related to the first phase current, includes: comparing the information related to the first phase current of any one of the U-phase, V-phase, and W-phase with a threshold A; if they are close, the sealing function is determined to be normal and the process ends; otherwise, the sealing function is determined to be abnormal and the process ends.

[0016] In a preferred embodiment of the present invention, when an output contactor is present, the following step may be added:

[0017] Step 4: Disconnect the three normally open contacts of the output contactor and proceed to Step 5;

[0018] Step 5: Keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 6;

[0019] Step Six: Output a larger voltage from any two or three of the U-phase, V-phase, and W-phase of the frequency converter, then proceed to Step Seven;

[0020] Step 7: Detect the position of the sealing contactor based on the information related to the second phase current.

[0021] In a preferred embodiment of the present invention, in step six, if any two of the U-phase, V-phase, and W-phase of the frequency converter output a large voltage, then steps six and seven need to be repeated twice, and the two pairs of phases are different in each repetition.

[0022] In a preferred embodiment of the present invention, step seven, which involves detecting the position of the sealing contactor based on phase current-related information, includes: comparing the information related to the second phase current of any one of the U-phase, V-phase, and W-phase with a threshold B; if they are close, then the sealing contactor is connected to the rear end of the output contactor; otherwise, the sealing contactor is connected to the front end of the output contactor and should be corrected.

[0023] To achieve the second objective of the invention mentioned above, the elevator sealing contactor detection method based on frequency converter-controlled permanent magnet synchronous motor of the present invention, when there is an output contactor, may include the following steps:

[0024] Step 1: Disconnect the three normally open contacts of the output contactor and proceed to Step 2.

[0025] Step 2: Keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 3.

[0026] Step 3: Output a larger voltage from any two or three of the U, V, and W phases of the frequency converter, and proceed to Step 4.

[0027] Step 4: Detect the position of the sealing contactor based on the information related to the second phase current.

[0028] In a preferred embodiment of the present invention, in step three', if any two of the U-phase, V-phase, and W-phase of the frequency converter output a large voltage, then steps three' and four' need to be repeated twice, and any two phases in the two repetitions are different.

[0029] In a preferred embodiment of the present invention, step four', detecting the position of the sealing contactor based on the information related to the second phase current, includes: comparing the phase current related information of any one of the U phase, V phase, and W phase with a threshold B; if they are close, it is determined that the sealing contactor is connected to the rear end of the output contactor; otherwise, it is determined that the sealing contactor is connected to the front end of the output contactor and should be corrected.

[0030] In a preferred embodiment of the present invention, after the sealing contactor is connected to the rear end of the output contactor, the following step is added:

[0031] Step 5: Close the output contactor to keep the PM motor stopped and the main contacts of the star-sealing contactor closed, then proceed to Step 6.

[0032] Step Six: Output a small voltage from any two or three of the U, V, and W phases of the frequency converter, then proceed to Step Seven.

[0033] Step 7: Perform a star-sealing function test based on the information related to the first phase current.

[0034] In a preferred embodiment of the present invention, in step six', if any two of the U-phase, V-phase, and W-phase of the frequency converter output a small voltage, then steps six' and seven' need to be repeated twice, and any two phases in the two repetitions are different.

[0035] In a preferred embodiment of the present invention, step seven', the star-sealing function detection based on the information related to the first phase current includes: comparing the information related to the phase current of any one of the U phase, V phase, and W phase with a threshold A; if they are close, the star-sealing function is judged to be normal and the process ends; otherwise, the star-sealing function is judged to be abnormal and the process ends.

[0036] To achieve the third objective of the invention mentioned above, the elevator sealing contactor detection method based on a frequency converter-controlled permanent magnet synchronous motor of the present invention includes the following steps when there is an output contactor and the sealing detection adopts a slip-and-go method and the hardware requires that the output contactor be closed before the brake can be released:

[0037] Step 1: Disconnect the three normally open contacts of the output contactor and proceed to Step 2.

[0038] Step Two: Keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step Three.

[0039] Step 3: Any two or three phases of the inverter's U-phase, V-phase, and W-phase output a larger voltage, then proceed to Step 4.

[0040] Step 4: Detect the position of the sealing contactor based on the information related to the second phase current.

[0041] In a preferred embodiment of the present invention, in step three, if any two of the U-phase, V-phase, and W-phase of the frequency converter output a large voltage, then steps three and four need to be repeated twice, and any two phases in the two repetitions are different.

[0042] In a preferred embodiment of the present invention, step four, which involves detecting the position of the sealing contactor based on the information related to the second phase current, includes: comparing the phase current related information of any one of the U-phase, V-phase, and W-phase with a threshold B; if they are close, then the sealing contactor is connected to the rear end of the output contactor; otherwise, the sealing contactor is connected to the front end of the output contactor and should be corrected.

[0043] In a preferred embodiment of the invention, the larger voltage has the following characteristic: it can generate a non-zero current when the inverter output is short-circuited.

[0044] In a preferred embodiment of the present invention, the larger voltage has the following characteristic: the time difference between the two-phase upper or lower drive signals output by the frequency converter is greater than the voltage output by the set dead time Td.

[0045] In a preferred embodiment of the present invention, the smaller voltage refers to the output voltage that, when controlled by two-phase or three-phase, generates a non-zero current when the output is not short-circuited or partially short-circuited, and generates a near-zero current when the output is short-circuited.

[0046] In a preferred embodiment of the present invention, the smaller voltage has the following characteristics: when the phase current is close to zero, the time difference between the output of the two phase upper or lower tube drive signals of the frequency converter is less than the voltage output by the set dead time Td.

[0047] In a preferred embodiment of the present invention, the phase current related information is one or any combination of two of the following: the phase current itself, the difference between phase currents, the sum of phase currents, frequency, impedance, and voltage.

[0048] In a preferred embodiment of the present invention, the threshold A is zero and the threshold B is zero.

[0049] In a preferred embodiment of the present invention, the output voltage is relatively small, which can be achieved by a control method that compensates through current feedback, so that when the output current is close to zero, the compensation voltage is small or close to zero, the compensation value increases as the output current increases, and the final compensation voltage is a limited value.

[0050] In a preferred embodiment of the present invention, the control method for compensation through current feedback may employ a dead-time compensation control method.

[0051] In a preferred embodiment of the present invention, the output of a small voltage does not require any compensation method, and the drive signal of the upper or lower transistor output by the frequency converter does not change with the current.

[0052] In a preferred embodiment of the present invention, a larger phase current signal is obtained by increasing the carrier frequency of the frequency converter.

[0053] In a preferred embodiment of the present invention, when the three-phase control outputs a small voltage, the output voltage vector of the frequency converter is at 60°*k+30°, where k = 0, 1, 2, 3, 4, or 5.

[0054] In a preferred embodiment of the present invention, when the three-phase control outputs a large voltage, the output voltage vector of the frequency converter is 60°*k, where k = 0, 1, 2, 3, 4, or 5.

[0055] This invention can detect whether the sealing contactor of an elevator is in an effective state (invalid states such as the sealing contactor not being installed, circuit interruption, or incorrect installation), without needing to release the brake, eliminating the risk of overshooting or undershooting, and posing no safety risk to passengers. The detection time is very short (a few hundred milliseconds), and it does not affect the use of the elevator. Attached Figure Description

[0056] Figure 1 This is a schematic diagram illustrating the connection principle between the frequency converter, the sealing contactor, and the motor.

[0057] Figure 2 This is a schematic diagram illustrating the connection principle between the frequency converter, output contactor, sealing contactor, and motor.

[0058] Figure 3 This is a flowchart illustrating the elevator sealing contactor detection method according to Embodiment 1 of the present invention.

[0059] Figure 4 This is a schematic diagram of the PWM signal and output voltage waveform when the UV output of the frequency converter is not short-circuited.

[0060] Figure 5 This is a schematic diagram of the PWM signal and output voltage waveform when the UV output of the frequency converter is short-circuited.

[0061] Figure 6 This is a schematic diagram of the impedance equivalent of the motor if a two-phase control method is adopted.

[0062] Figure 7 This is a schematic diagram showing the open states of the main contacts of the sealing contactor. a) Only the UV contacts are open, b) Only the VW contacts are open, and c) Both UV and W contacts are open.

[0063] Figure 8 Schematic diagram of output voltage vector for three-phase control

[0064] Figure 9 This is a schematic diagram of the equivalent motor impedance when the main contacts of the sealing contactor are open and the three-phase control voltage vector is at 90°. Where a) represents the case where only UV is disconnected and UVW is fully disconnected, and b) represents the case where only VW is disconnected.

[0065] Figure 10 This is a schematic diagram showing the connection of the sealing contactor to the front end of the output contactor.

[0066] Figure 11 This is a flowchart illustrating the elevator sealing contactor detection method according to Embodiment 2 of the present invention.

[0067] Figure 12 This is a flowchart illustrating the elevator sealing contactor detection method according to Embodiment 3 of the present invention. Detailed Implementation

[0068] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0069] Example 1

[0070] See Figure 1 and Figure 3 This embodiment describes a method for detecting a star-shaped contactor used in elevators based on a frequency converter-controlled permanent magnet synchronous motor, comprising the following steps:

[0071] Step 1: When there is no output contactor, keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 2; when there is an output contactor, close the output contactor to keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 2.

[0072] Step 2: Output a small voltage to any two of the U, V, and W phases of the inverter (in two-phase control, the PWM of the third phase is disabled, and the third phase winding of the PM motor is in a floating state) or all three phases, and proceed to Step 3;

[0073] Step 3: Compare the information related to the first phase current of any one of the U-phase, V-phase, and W-phase with the threshold A. If they are close, the star-sealing function is considered normal and the process ends; otherwise, the star-sealing function is considered abnormal and the process ends.

[0074] In step two above, if any two of the inverter's U-phase, V-phase, and W-phase output a small voltage, then steps two and three need to be repeated twice, with each pair of phases being different.

[0075] The smaller voltage mentioned in step two above refers to the output voltage during two-phase or three-phase control, which can generate a non-zero current when the output is not short-circuited or partially short-circuited, and generate a near-zero current when the output is short-circuited.

[0076] Furthermore, the smaller voltage mentioned in step two above has the following characteristics: when the phase current is close to zero, the time difference between the output of the upper or lower phase drive signals of the inverter is less than the voltage output by the set dead time Td.

[0077] The phase current-related information mentioned in step three above is one or any combination of two of the following: the phase current itself, the difference between phase currents, the sum of phase currents, frequency, impedance, and voltage.

[0078] The threshold A mentioned in step three above is zero.

[0079] The relatively small output voltage in step two above can be compensated using a current feedback control method. This ensures that when the output current is close to zero, the compensation voltage is small or close to zero, and the compensation value increases as the output current increases, ultimately reaching a predetermined value. Specifically, the current feedback compensation control method can employ a dead-time compensation control method.

[0080] In step two above, a smaller output voltage can be achieved without any compensation method, and the drive signal of the upper or lower transistor output by the frequency converter does not change with the current.

[0081] In addition, this embodiment can obtain a larger phase current signal by increasing the carrier frequency of the inverter.

[0082] The output voltage vector of the inverter in this embodiment is 60°*k+30°, where k = 0, 1, 2, 3, 4, or 5.

[0083] It should be noted that, referring to Chinese patent CN1300925C, in order to prevent short circuits in the switching elements of the upper or lower bridge arm of the frequency converter, a dead time needs to be inserted between the drive signal of the upper bridge arm and the drive signal of the lower bridge arm.

[0084] See Figure 1 and Figure 4 When the main contacts of the star-connector at the inverter output are open (without an external short circuit to the inverter), within the PWM carrier period T, a) is the ideal PWM drive signal; b) and c) are the actual drive signals after adding the dead time Td, respectively. The U-phase output voltage UO of the inverter is the U-phase output voltage relative to the neutral line "O", and the neutral ground line "O" is the assumed neutral line of the DC bus PN. The positive direction of the phase current is the direction of outflow from the inverter.

[0085] Assuming i_U > 0, during the dead time, both switching elements T1 and T4 are not conducting. However, due to the inductive load, the output current must be continuous. Therefore, the current flows through the freewheeling diode D4 to maintain the continuity of the output current, and a negative DC voltage is connected to the output terminal. Similarly, when the output current flows into the inverter, i.e., i_V < 0, during the dead time, the output current flows through the freewheeling diode D2, and the inverter output terminal has a positive voltage. Assuming the switching elements are ideal, meaning that the voltage drop and switching time of the switching elements can be ignored... Figure 1 and Figure 4 In the equations e) and j), the output voltage error caused by the dead time has the same voltage height Ud and the same pulse width Td, and is opposite to the current direction regardless of the current direction. Therefore, the magnitude of the output current is reduced regardless of the polarity of the output current.

[0086] Figure 1 and Figure 4 In sections d) and e), the bold solid lines represent the case of a larger positive current flowing out, while the dashed lines represent the case of a smaller positive current flowing out. For a larger positive current flowing out, the inductive effect causes UO to drop rapidly to a low voltage during the dead time. However, for a smaller positive current, UO is difficult to reduce during the dead time due to the longer cutoff time, parasitic inductance, and system capacitance. Therefore, the high voltage UO decays slowly during the dead time, reducing the voltage error caused by the dead time. When the positive current is small enough, UO may reach its maximum value, represented by the uppermost dashed line in section d). The error portion, as shown by the dashed line in e), will have zero error throughout the entire PWM cycle, meaning the error caused by the dead time is completely automatically compensated.

[0087] Similarly, for negative currents, VO increases slowly, such as... Figure 1 and Figure 4 As shown in i), the voltage error caused by the dead time gradually decreases as the current decreases. That is, when the output current is large, the voltage error caused by the dead time is quite large, while when the output current is small, the error is quite small. In order to reduce the voltage error caused by the dead time, the frequency converter usually performs dead time compensation control. That is, when the polarity of the output current is negative, the compensation voltage Vcomp is negative; when the output current is positive, the compensation voltage Vcomp is positive, and Vcomp is related to the current magnitude. When the current is small enough, the compensation voltage Vcomp is 0, and when the current is large enough, the compensation voltage is a constant value (Td / T*Ud).

[0088] See Figure 1 and Figure 5 When the main contacts of the inverter's output star contactor are closed (i.e., when the inverter's output is short-circuited), a short circuit will occur if the drive signal SU of the upper U-phase tube T1 overlaps with the drive signal SY of the lower V-phase tube T5 (or if the drive signal SX of the lower U-phase tube T4 overlaps with the drive signal SV of the upper V-phase tube T2). At this time, a large current will be generated in both U and V phases, triggering overcurrent protection. However, when the drive signal SU of the upper U-phase tube T1 does not overlap with the drive signal SY of the lower V-phase tube T5 (i.e., the time difference T_UV between the drive signal SU of the upper U-phase tube T1 and the drive signal SV of the upper V-phase tube T2 is less than the set dead time Td), the output voltage is not determined independently by each drive signal, but rather jointly, resulting in the same output voltage, i.e., the phase-to-phase voltage difference is 0, and the current of the external load (such as a PM motor) is 0.

[0089] As mentioned above, when the main contacts of the inverter output star contactor are open (i.e., when there is no short circuit at the inverter output), the voltage error caused by the dead time significantly reduces the load current when the time difference T_UV between the drive signal SU of phase U upper transistor T1 and the drive signal SV of phase V upper transistor T2 is less than the set dead time Td. For example, for a 15kW inverter with a rated current of 32A, a PWM carrier frequency of 10kHz, a set dead time of 2µs, a motor phase resistance of 0.25Ω, and an inductance of 5mH, when the bus voltage is 500V, the maximum voltage error caused by the dead time is 10V. When only UV is used for PWM control (i.e., two-phase control, with PWM disabled for phase W and the motor phase W winding in a floating state), the motor is equivalent to... Figure 6 The UV two-phase impedance is connected in series (its equivalent impedance is twice the phase impedance). When the time difference of the UV upper transistor drive signal is 0.5µs, the expected UV output voltage difference is 5V, and the expected motor current is 10A. However, due to the dead time, the actual UV output voltage is less than 0.5V, and the current is less than 1A. With appropriate dead time compensation control, the actual UV output voltage can reach the expected output voltage of 5V, and the motor current can reach 10A. At this time, the time difference of the UV upper transistor drive signal is greater than 2µs. That is, after adopting dead time compensation control, the time difference of the UV upper transistor drive signal will automatically change with the magnitude of the output current. When the output current is close to 0, because the compensated voltage is close to 0, the UV upper transistor drive signal time difference is close to the initial 0.5µs. This voltage generates a small current. As the compensation value increases with the increase of the output current, the output voltage eventually reaches the expected 5V. The UV upper transistor drive signal time difference is the initial time difference plus the time corresponding to the final compensation value.

[0090] Therefore, by outputting a small voltage between the UV and V phases of the inverter, it can be determined whether the phase current flowing through the U and V phases is close to zero, thus distinguishing whether the main contacts of the star-sealed contactor at the UV output terminal of the inverter are closed. When the phase current flowing through the U and V phases is close to zero, it indicates that the main contacts of the star-sealed contactor are closed; when the phase current flowing through the U or V phase is not close to zero, it indicates that the main contacts of the star-sealed contactor are open.

[0091] Furthermore, the small voltage output between the UV and V phases of the inverter has the following characteristics: it generates a non-zero current when the UV output of the inverter is not short-circuited, and generates a near-zero current when the UV output is short-circuited. Preferably, this small voltage has the characteristic that when the phase current is close to zero, the time difference between the drive signals of the upper transistors of the UV and V phases is less than the set dead time Td. When the dead time compensation control technology used can fully compensate for the voltage distortion caused by the dead time, circuit delay, and switching transistor voltage drop, the time difference can be further reduced, that is, the current generated by the ideal output voltage related to this time difference applied to the external load can be clearly distinguished as non-zero. As in the example above, when the inverter uses a 12-bit AD converter, it can clearly distinguish that 1A is not zero, and the time difference can be reduced to 0.1µs.

[0092] It should be noted that the small output voltage can also be achieved without dead time compensation control technology. In this case, when the main contacts of the sealing contactor open and close, regardless of the output current, the time difference between the drive signals of the upper tubes of the UV two phases is the same, that is, the initial value.

[0093] See Figure 7 a) The main contacts of the star-sealing contactor are open only for UV; b) The main contacts of the star-sealing contactor are open only for VW; c) The main contacts of the star-sealing contactor are open for both UV and W. By outputting a small voltage as described above between the two phases UV and V and between the two phases V and W respectively, if the phase currents flowing through the U and V phases and the phase currents flowing through the V and W phases are close to zero, the star-sealing function is normal. However, if any phase current is not close to zero, the star-sealing function is abnormal.

[0094] See further Figure 8 The frequency converter uses three-phase control, and when the output voltage vector is at 90° (U-phase voltage is at its maximum positive direction, and V and W are equal in negative direction), when all the main contacts UVW of the star-connector at the frequency converter output are open, such as... Figure 7 In the middle, c), or the main contacts of the star-sealed contactor are only disconnected at UV, such as Figure 7 In case a), the motor is equivalent to Figure 9 The two-phase impedance shown in a) is connected in parallel and then in series with another phase, resulting in an equivalent impedance of 1.5 times the phase impedance. However, when only VW of the main contacts of the star-sealed contactor is open, as shown in a diagram... Figure 7 In case b), the motor is equivalent to Figure 9 As shown in b), the two-phase impedances connected in parallel and then in series with another phase have an equivalent impedance of 1.5 times the phase impedance. Therefore, under the same output line voltage, when the output voltage vector is at 90°, the maximum value of the phase current is... Figure 6The two-phase control shown is 4 / 3 times stronger, making it easier to distinguish whether the current is close to zero. Furthermore, at this point, with just a small voltage output, it can be determined whether the phase current of any one of the U, V, or W phases is close to zero, thus determining whether the star-sealing function is normal. That is, when the phase current of any one of the U, V, or W phases is close to zero, the star-sealing function is normal; while when the U phase current is not close to zero, or when the V phase current is not close to zero, or when the W phase current is not close to zero, the star-sealing function is abnormal.

[0095] Further, see Figure 8 In three-phase control, the inverter's output voltage vector can achieve the above effect when it is 60°*k+30° (k=0, 1, 2, 3, 4, 5). It should be noted that three-phase control can also be used for satellite detection at other voltage vectors, but it will not be optimal.

[0096] In some low-power motor applications, such as a three-phase permanent magnet motor for a household elevator with a power of 1.1kW, a phase resistance of 5 ohms, and an inductance of 100mH, when outputting a low voltage, considering that existing simple dead-time compensation control techniques are insufficient to completely compensate for distorted voltage, in order to further increase the phase current when the main contacts of the star-sealed contactor are open, to distinguish it from the current approaching zero when the main contacts of the star-sealed contactor are fully closed, this can be achieved by increasing the PWM carrier frequency (i.e., reducing...). Figure 4 , Figure 5 The period T in the signal makes the actual output voltage larger when the two phase upper transistor drive signals have the same time difference (e.g., Figure 4 k), with an average voltage of Δt / T*Ud), resulting in a larger and more easily identifiable output current.

[0097] It should be noted that the electrical time constant of a typical three-phase permanent magnet motor is relatively small. For example, the phase resistance of the motor mentioned above is 0.25Ω and the inductance is 5mH. Its electrical time constant is 20ms. Therefore, the output phase current can reach a steady state after applying a small voltage for 100ms, and its satellite detection time is only a few hundredms.

[0098] Example 2

[0099] See Figure 2 When an output contactor exists at the inverter's output, the effective star-sealing function requires ensuring that the star-sealing contactor is connected to the rear end of the output contactor, not the front end (e.g., ...). Figure 10 When the sealing detection only uses the slippage method and the hardware requires the output contactor to be closed before the brake can be released (due to regulatory requirements, the disengagement of the brake requires two independent electromechanical devices; to reduce costs, most elevator control systems currently use a single brake contactor and an auxiliary contact of the output contactor), because the output contactor is closed during slippage, it is impossible to determine whether the sealing contactor is connected to the front or back end of the output contactor.

[0100] The elevator sealing contactor detection method based on frequency converter-controlled permanent magnet synchronous motor in this embodiment is used to detect whether the sealing contactor is connected to the front or rear end of the output contactor. See [link to relevant documentation] Figure 11 It includes the following steps:

[0101] Step 1: Disconnect the three normally open contacts of the output contactor and proceed to Step 2.

[0102] Step 2: Keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 3.

[0103] Step 3: Output a larger voltage from any two or three of the U, V, and W phases of the frequency converter, and proceed to Step 4.

[0104] Step 4: Compare the information related to the second phase current of any one of the U-phase, V-phase, and W-phase with the threshold B. If they are close, it is determined that the star-sealed contactor is connected to the rear end of the output contactor; otherwise, it is determined that the star-sealed contactor is connected to the front end of the output contactor and should be corrected.

[0105] If, in step three', any two of the inverter's U-phase, V-phase, and W-phase output a large voltage, then steps three' and four' need to be repeated twice, with each pair of phases being different.

[0106] See Figure 4 In step three, a larger voltage has the following characteristics: it can generate a non-zero current when the inverter output is short-circuited. Preferably, the time difference between the two phase upper or lower drive signals of the inverter output is greater than the voltage output by the set dead time Td.

[0107] The information related to the second phase current mentioned in step four above is one or any combination of two of the following: the phase current itself, the difference between phase currents, the sum of phase currents, frequency, impedance, and voltage.

[0108] The threshold B mentioned in step four above is zero.

[0109] In this embodiment, the output voltage vector of the frequency converter under three-phase control is at 60°*k, where k = 0, 1, 2, 3, 4, or 5. See also... Figure 8 At this time, the three-phase output voltages of U, V, and W are significantly unequal, which makes it easier to determine whether the inverter output is short-circuited.

[0110] After the sealing contactor is connected to the rear end of the output contactor, the following steps can be added to this embodiment:

[0111] Step 5: Close the output contactor to keep the PM motor stopped and the main contacts of the star-sealing contactor closed, then proceed to Step 6.

[0112] Step Six: Output a small voltage from any two or three of the U, V, and W phases of the frequency converter, then proceed to Step Seven.

[0113] Step 7: Compare the phase current-related information of any one of the U-phase, V-phase, and W-phase to the same threshold. If they are close, the star-sealing function is considered normal and the process ends; otherwise, the star-sealing function is considered abnormal and the process ends.

[0114] If, in step six', any two of the inverter's U-phase, V-phase, and W-phase output a small voltage, then steps six' and seven' need to be repeated twice, with each pair of phases being different.

[0115] This embodiment has the same voltage definition as Embodiment 1 for smaller voltages.

[0116] Example 3

[0117] See Figure 2 When an output contactor is present at the inverter's output, for the star-sealing function to be effective, it is necessary not only to ensure that the star-sealing contactor is connected to the downstream end of the output contactor, but also to confirm that the star-sealing circuit is not disconnected. See also Figure 2 , Figure 12 The elevator sealing contactor detection method based on frequency converter controlled permanent magnet synchronous motor in this embodiment includes the following steps:

[0118] Step 1: Disconnect the three normally open contacts of the output contactor and proceed to Step 2.

[0119] Step Two: Keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step Three.

[0120] Step 3: Any two or three phases of the inverter's U-phase, V-phase, and W-phase output a larger voltage, then proceed to Step 4.

[0121] Step 4: Compare the information related to the second phase current of any one of the U-phase, V-phase, and W-phase with the threshold B. If they are close, it is determined that the star-sealed contactor is connected to the rear end of the output contactor; otherwise, it is determined that the star-sealed contactor is connected to the front end of the output contactor and should be corrected.

[0122] See Figure 4 In step three, a larger voltage has the following characteristics: it can generate a non-zero current when the inverter output is short-circuited. Preferably, the time difference between the two phase upper or lower drive signals of the inverter output is greater than the voltage output by the set dead time Td.

[0123] Step 5: Close the three-phase normally open contacts of the output contactor to proceed to Step 6.

[0124] Step Six: Keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step Seven.

[0125] Step Seven: Output a small voltage from any two or three of the U, V, and W phases of the frequency converter, and proceed to Step Eight.

[0126] Step 8: Compare the information related to the first phase current of any one of the U-phase, V-phase, and W-phase with the threshold A. If they are close, the star-sealing function is considered normal and the process ends; otherwise, the star-sealing function is considered abnormal and the process ends.

[0127] In step three, if any two of the inverter's U-phase, V-phase, and W-phase output a large voltage, then steps three and four need to be repeated twice, with each pair of phases being different.

[0128] In step seven, if one or any two of the inverter's U-phase, V-phase, and W-phase outputs a small voltage, then steps seven and eight need to be repeated twice, with the two pairs of phases being different.

[0129] The definition of larger voltages in this embodiment is the same as in Embodiment 2, and the definition of smaller voltages is the same as in Embodiment 1.

[0130] The voltage applied in the above embodiments is not limited to DC, but can also be AC.

Claims

1. A method for detecting a star-shaped contactor for elevators based on a frequency converter-controlled permanent magnet synchronous motor, characterized in that, Includes the following steps: Step 1: When there is no output contactor, keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 2; when there is an output contactor, close the output contactor, keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 2. Step 2: Output a small voltage from any two or three phases of the inverter's U-phase, V-phase, and W-phase, then proceed to Step 3; Step 3: Perform a star-sealing function test based on the information related to the first phase current; The process of detecting the sealing function based on the information related to the first phase current includes: comparing the information related to the phase current of any one of the U-phase, V-phase, and W-phase with a threshold A. If they are close, the sealing function is considered normal and the process ends; otherwise, the sealing function is considered abnormal and the process ends.

2. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 1, characterized in that, In step two, if any two of the inverter's U-phase, V-phase, and W-phase output a small voltage, then steps two and three need to be repeated twice, with each pair of phases being different.

3. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 1, characterized in that, When there is an output contactor, add the following steps: Step 4: Disconnect the three normally open contacts of the output contactor and proceed to Step 5; Step 5: Keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 6; Step Six: Output a larger voltage from any two or three of the U-phase, V-phase, and W-phase of the frequency converter, then proceed to Step Seven; Step 7: Detect the position of the sealing contactor based on the information related to the second phase current; The method of detecting the position of the sealing contactor based on the information related to the second phase current includes: comparing the phase current related information of any one of the U phase, V phase, and W phase with a threshold B; if they are close, it is determined that the sealing contactor is connected to the rear end of the output contactor; otherwise, it is determined that the sealing contactor is connected to the front end of the output contactor and should be corrected.

4. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 3, characterized in that, In step six, if any two of the inverter's U-phase, V-phase, and W-phase output a large voltage, then steps six and seven need to be repeated twice, with each pair of phases being different.

5. A method for detecting a star-type contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, characterized in that, when there is an output contactor, Includes the following steps: Step 1: Disconnect the three normally open contacts of the output contactor and proceed to Step 2. Step 2: Keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step 3. Step 3: Output a larger voltage from any two or three of the U, V, and W phases of the frequency converter, and proceed to Step 4. Step 4: Detect the position of the sealing contactor based on the information related to the second phase current; The method of detecting the position of the sealing contactor based on the information related to the second phase current includes: comparing the phase current related information of any one of the U phase, V phase, and W phase with a threshold B; if they are close, it is determined that the sealing contactor is connected to the rear end of the output contactor; otherwise, it is determined that the sealing contactor is connected to the front end of the output contactor and should be corrected.

6. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 5, characterized in that, In step three', if any two of the inverter's U-phase, V-phase, and W-phase output a large voltage, then steps three' and four' need to be repeated twice, with each pair of phases being different.

7. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 5, characterized in that, After the sealing contactor is connected to the rear end of the output contactor, the following steps are added: Step 5: Close the output contactor to keep the PM motor stopped and the main contacts of the star contactor closed, then proceed to Step 6. Step Six: Output a small voltage from any two or three of the U, V, and W phases of the frequency converter, then proceed to Step Seven. Step 7: Perform a star-sealing function test based on the information related to the first phase current.

8. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 7, characterized in that, In step six', if any two of the inverter's U-phase, V-phase, and W-phase output a small voltage, then steps six' and seven' need to be repeated twice, with each pair of phases being different.

9. A method for detecting a star-shaped contactor for elevators based on a frequency converter-controlled permanent magnet synchronous motor, characterized in that, When there is an output contactor and the star-sealing detection uses a runaway method and the hardware requires the output contactor to be closed before the brake can be released, the following steps are included: Step 1: Disconnect the three normally open contacts of the output contactor and proceed to Step 2. Step Two: Keep the PM motor stopped and the main contacts of the sealing contactor closed, then proceed to Step Three. Step 3: Any two or three phases of the inverter's U-phase, V-phase, and W-phase output a larger voltage, then proceed to Step 4. Step 4: Detect the position of the sealing contactor based on the information related to the second phase current; The method of detecting the position of the sealing contactor based on the information related to the second phase current includes: comparing the phase current related information of any one of the U phase, V phase, and W phase with a threshold B; if they are close, it is determined that the sealing contactor is connected to the rear end of the output contactor; otherwise, it is determined that the sealing contactor is connected to the front end of the output contactor and should be corrected.

10. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 9, characterized in that, In step three, if any two of the inverter's U-phase, V-phase, and W-phase output a large voltage, then steps three and four need to be repeated twice, with each pair of phases being different.

11. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 7, characterized in that, The process of detecting the sealing function based on the information related to the first phase current includes: comparing the information related to the phase current of any one of the U-phase, V-phase, and W-phase with a threshold A. If they are close, the sealing function is considered normal and the process ends; otherwise, the sealing function is considered abnormal and the process ends.

12. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 3, 4, 5, 6, 9, or 10, characterized in that... The larger voltage has the following characteristic: it can generate a non-zero current when the inverter output is short-circuited.

13. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 12, characterized in that, The larger voltage has the following characteristics: the time difference between the two phase upper or lower drive signals output by the frequency converter is greater than the voltage output by the set dead time Td.

14. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 1, 2, 7, or 8, characterized in that... The aforementioned smaller voltage refers to the output voltage during two-phase or three-phase control, which can generate a non-zero current when the output is not short-circuited or partially short-circuited, and generate a near-zero current when the output is short-circuited.

15. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 14, characterized in that, The smaller voltage has the following characteristics: when the phase current is close to zero, the time difference between the output of the upper or lower phase drive signals of the inverter is less than the voltage output by the set dead time Td.

16. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 1, 2, 7, or 8, characterized in that... The information related to the first phase current is one or any combination of two of the following: the phase current itself, the difference between phase currents, the sum of phase currents, frequency, impedance, and voltage.

17. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 3, 4, 5, 6, 9, or 10, characterized in that... The information related to the second phase current is one or any combination of two of the following: the phase current itself, the difference between the phase currents, the sum of the phase currents, frequency, impedance, and voltage.

18. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 1 or 11, characterized in that... The threshold A is zero.

19. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 3, 5, or 9, characterized in that... The threshold B is zero.

20. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 1, 2, 7, or 8, characterized in that... The relatively small voltage can be compensated by a control method using current feedback, so that when the output current is close to zero, the compensation voltage is small or close to zero, the compensation value increases as the output current increases, and the final compensation voltage is a limited value.

21. The method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor as described in claim 20, characterized in that, The control method that uses current feedback for compensation is the dead time compensation control method.

22. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 1, 2, 7, or 8, characterized in that... The smaller voltage does not employ any compensation method, and the drive signal of the upper or lower transistor output by the frequency converter does not change with the current.

23. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 1, 2, 7, or 8, characterized in that... A larger phase current signal can be obtained by increasing the carrier frequency of the frequency converter.

24. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 1, 2, 7, or 8, characterized in that... When the three-phase control outputs a small voltage, the inverter's output voltage vector is at 60°*k+30°, where k = 0, 1, 2, 3, 4, or 5.

25. A method for detecting a star-shaped contactor for an elevator based on a frequency converter-controlled permanent magnet synchronous motor, as described in claim 3, 4, 5, 6, 9, or 10, characterized in that... When the three-phase control outputs a large voltage, the output voltage vector of the frequency converter is at 60°*k, where k = 0, 1, 2, 3, 4, or 5.

Images