JP2011182505A - Sensorless synchronous motor drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensorless synchronous motor drive for controlling a rotor so that the rotor stops at a prescribed position reliably upon lock energization for locking the rotor at a prescribed position when starting the synchronous motor. <P>SOLUTION: In a lock energization process when starting the synchronous motor 10, on-duty of a pulse signal inputted to a switching element Q1 of an inverter circuit 2 from a predrive circuit 4 is increased gradually based on a lock energization control signal outputted from a lock energization control circuit 5 of a control circuit unit 3 to the predrive circuit 4, thus increasing a lock current Iu flowing a U-phase drive coil Lu gradually until the lock current Iu reaches a prescribed value I2, and hence preventing a large current exceeding the prescribed value I2 from flowing the U-phase drive coil Lu, preventing out of synchronization in the synchronous motor 10, and controlling the rotor so that the rotor stops at the prescribed position reliably. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sensorless synchronous motor driving apparatus that drives a motor without using a rotor (rotor) position sensor, and more particularly, to a sensorless synchronous motor driving apparatus that can prevent a step-out when a rotor is energized at startup.

  2. Description of the Related Art Conventionally, a sensorless synchronous motor that detects the position of a rotor using an induced voltage generated in a drive coil by the rotation of the rotor without detecting the position of the rotor (rotor) by a Hall element or the like is known (for example, Patent Document 1).

JP 2008-48506 A

However, in a sensorless synchronous motor such as that disclosed in Patent Document 1, when a lock energization is performed to lock the rotor at a predetermined position during startup, a large lock current flows through the drive coil, and the rotor does not stop at the predetermined position. There is a problem that the problem of stepping out occurs. In particular, when a lock motor is used for a motor having a small cogging torque or a fan motor having a large blade, the probability of stepping out due to an inertial force accompanying rotation generated when a large lock current flows increases.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a simple circuit configuration, but the rotor reliably stops at a predetermined position when a lock energization is performed to lock the rotor at a predetermined position during startup. An object of the present invention is to provide a sensorless synchronous motor driving device that can be controlled in this manner.

In order to achieve the above object, a sensorless synchronous motor driving apparatus according to the invention of claim 1 is based on back electromotive voltages generated in a plurality of phase driving coils without using a sensor for detecting the position of a rotor. A sensorless synchronous motor driving apparatus having an inverter circuit for selectively energizing a coil, and a predrive circuit for outputting a drive signal to the inverter circuit, and for locking the rotor at a predetermined position when the motor is started A lock energization control circuit that controls the pre-drive circuit so that a lock current flows from the inverter circuit to the drive coil, and the lock energization control circuit has a predetermined magnitude of the lock current. A signal that is controlled to increase over a predetermined time until reaching a value is output to the pre-drive circuit. And features.

According to a second aspect of the present invention, in the sensorless synchronous motor driving device according to the first aspect, the inverter circuit is provided for each phase so that a driving current flows for each phase of the plurality of phase driving coils. A high-side switching element and a low-side switching element, and the adjustment of the magnitude of the lock current is performed by a drive signal input to the high-side switching element and the low-side switching element provided for each phase from the pre-drive circuit. Is controlled by the lock energization control circuit.

According to a third aspect of the present invention, in the sensorless synchronous motor driving device according to the second aspect, the adjustment of the magnitude of the lock current is performed by any one of the plurality of driving coils from the pre-drive circuit. It is performed by varying the on-duty of the pulse signal input to the high-side switching element and / or the low-side switching element provided in the phase.

According to a fourth aspect of the present invention, in the sensorless synchronous motor driving device according to the second or third aspect, the predrive circuit is a high side provided in one of the plurality of phase driving coils. A pulse signal whose on-duty increases with time until the magnitude of the lock current reaches a predetermined value is input to the switching element, and a low-side switching element provided in the one phase and a high level of each phase excluding the one phase. A low-level driving signal is input to the side switching element, and a high-level driving signal is input to the low-side switching element of each phase except the one phase.

Since the sensorless synchronous motor driving device according to the present invention is configured as described above, the rotor is surely brought into a predetermined position when the energization is performed to lock the rotor in a predetermined position at the time of start-up while having a simple circuit configuration. It is possible to provide a sensorless synchronous motor driving device that can be controlled to stop.

It is a circuit block diagram which shows the sensorless synchronous motor drive device which concerns on one Embodiment of this invention. It is a flowchart regarding operation | movement of the sensorless synchronous motor drive device which concerns on one Embodiment of this invention. It is a flowchart of the control routine of the lock energization process in the sensorless synchronous motor drive device concerning one embodiment of the present invention. In a sensorless synchronous motor drive device according to an embodiment of the present invention, (a) is a timing chart showing the correlation of drive signal waveforms input to each switching element of an inverter circuit when a lock is energized, and (b) is a U-phase drive coil. It is explanatory drawing which shows the time change of the lock current which flows into. It is a timing chart which shows the correlation of the drive signal waveform input into each switching element of the inverter circuit in other control modes by a lock energization control circuit.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a circuit configuration diagram showing a sensorless synchronous motor driving apparatus according to an embodiment of the present invention, and FIG. 2 is a flowchart regarding the operation of the sensorless synchronous motor driving apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the sensorless synchronous motor drive device 1 according to the present embodiment includes an inverter circuit 2 that controls the rotation of the synchronous motor 10 by supplying a drive current to the drive coil of each phase of the synchronous motor 10, and an inverter And a control circuit unit 3 that controls the operation of the circuit 2. The synchronous motor 10 in this embodiment is a three-phase motor having U-phase, V-phase, and W-phase drive coils Lu, Lv, and Lw, and is a sensorless synchronous motor that does not have a sensor for detecting the position of the rotor. is there.

The inverter circuit 2 includes six switching elements Q1 to Q6 for supplying driving currents to the driving coils Lu, Lv, and Lw of the synchronous motor 10, and the switching elements Q1, Q3, and Q5 are connected to the DC power source Vcc. P-channel MOSFET (Metal-Oxide-Semiconductor) placed on the positive electrode side
The switching elements Q2, Q4, and Q6 are low-side switching elements including N-channel MOSFETs disposed on the negative electrode side of the DC power supply Vcc. In the six switching elements, Q1 and Q2, Q3 and Q4, and Q5 and Q6 are connected in series, and the series circuits are connected in parallel to form a bridge circuit. The connection point of the switching elements Q1, Q2 is connected to the U-phase drive coil Lu, the connection point of the switching elements Q3, Q4 is connected to the V-phase drive coil Lv, and the connection point of the switching elements Q5, Q6 is the W-phase drive coil It is connected to the drive coil Lw.

The control circuit unit 3 outputs a drive signal to the inverter circuit 2 and a lock energization control signal at the time of energizing the lock to lock the rotor in a predetermined position when the synchronous motor 10 is started. 4 and a motor drive control circuit 6 for controlling the operation from forced commutation to sensorless drive after the lock energization. The control circuit unit 3 is a DSP (Digital
It can be configured using a programmable device such as a signal processor (FPGA), a field programmable gate array (FPGA), and a microcomputer.

  The pre-drive circuit 4 includes a plurality of output terminals connected to the respective gate terminals of the six switching elements Q1 to Q6 of the inverter circuit 2, and outputs a drive signal from the output terminal, thereby switching the switching elements Q1 to Q1. Controls the on / off operation of Q6. The inverter circuit 2 selectively energizes each drive coil based on the back electromotive voltage generated in each phase drive coil Lu, Lv, Lw of the synchronous motor 10.

  Here, the basic operation of the sensorless synchronous motor driving apparatus 1 will be briefly described.

  As shown in FIG. 2, the sensorless synchronous motor drive device 1 has a control circuit 3 constituted by a microcomputer or the like so as to conform to the drive conditions of the synchronous motor 10 when starting activation in the motor drive initial setting step. Are set (port, timer, etc.) (step S1).

  Next, the process proceeds to the lock energization process, and the lock energization control circuit 5 outputs a lock energization control signal to the predrive circuit 4, and the predrive circuit 4 turns on the switching elements Q1 to Q6 of the inverter circuit 2 according to the lock energization control signal. / Off operation is performed, a lock current flows through the drive coils Lu, Lv, Lw of each phase (U phase, V phase, W phase) of the synchronous motor 10, and the rotor of the synchronous motor 10 is locked at a predetermined position. (Step S2). Details of the operation in this step will be described later.

  Next, the process proceeds to a forced commutation step, and a drive control signal is output from the motor drive control circuit 6 to the predrive circuit 4. The predrive circuit 4 turns on / off the switching elements Q1 to Q6 of the inverter circuit 2 according to the drive control signal. An off operation is performed, and a drive current sequentially flows through the drive coils Lu, Lv, Lw of each phase (U phase, V phase, W phase) of the synchronous motor 10, and the rotational speed of the rotor gradually increases to a constant speed ( Step S3).

  Next, the process proceeds to the energization timing estimation step. When the rotor reaches a constant rotational speed, steady sensorless driving is started, and the control circuit unit 3 detects the zero cross point from the change in the induced voltage of each phase. Is estimated (step S4).

Then, the process proceeds to the energization switching step, and the motor drive control circuit 6 switches energization to each phase at the energization timing estimated by the control circuit unit 3, and continues the constant speed rotation of the synchronous motor 10 (step S5).

  As described above, the sensorless synchronous motor drive device 1 according to the present embodiment performs a steady rotation operation through the operation steps of FIG.

Next, a specific operation method of the lock energization process, which is a characteristic part of the present invention, will be described with reference to FIGS.

  FIG. 3 is a flowchart of the control routine of the lock energization process in the sensorless synchronous motor drive device 1, and FIG. 4 is a diagram of the sensorless synchronous motor drive device 1 according to the embodiment of the present invention. The timing chart which shows the correlation of the drive signal waveform input into each switching element Q1-Q6 of the circuit 2, (b) is explanatory drawing which shows the time change of the lock current Iu which flows into the U-phase drive coil Lu.

  As shown in FIG. 3, when the lock energization of the rotor is started at a predetermined time, the lock energization control circuit 5 outputs a lock energization control signal to the predrive circuit 4, and in step S11, the predrive circuit 4 Then, a gate drive signal based on the lock energization control signal is input to the inverter circuit 2. At this time, a pulse signal is input as a gate drive signal to a specific switching element among the switching elements Q1 to Q6 of the inverter circuit 2, and a high level gate drive signal or a low level gate is input to the other switching elements. One of the drive signals is input.

  Next, in step S12, the first gate drive signal is continuously input until the input time reaches a predetermined time t0. When the input time reaches the predetermined time t0, “YES” is determined in step S12. Proceed to step S13.

  Next, in step S13, it is determined whether the on-duty of the pulse signal input to the specific switching element is a preset maximum value. If the maximum value is not reached, "NO" is determined, and the process proceeds to step S14. move on.

  In step S14, the on-duty of the pulse signal is increased, the process returns to step S11, and the pulse signal with the increased on-duty is input to the specific switching element. And it progresses to step S12 and step S13, and when it becomes "NO" again in step S13, the operation | movement after step S14 is repeated.

  In step S13, when the on-duty of the pulse signal input to the specific switching element reaches the preset maximum value, “YES” is determined, and the process proceeds to step S15.

  In step S15, it is determined whether or not the lock energization time of the rotor has reached a predetermined time T3 set in advance. If not, “NO” is determined, and the process returns to step S12 to repeat the subsequent steps.

  If it is determined in step S15 that the lock energization time of the rotor has reached a predetermined time T3 set in advance, “YES” is set, and the lock energization process of the rotor is terminated.

  Next, the operation | movement by an example of the control mode of the lock energization control circuit 5 is demonstrated using FIG.

  4A, S1 to S6 indicate waveforms of drive signals (gate drive signals) input to the gate terminals of the switching elements Q1 to Q6 of the inverter circuit 2, respectively.

When the lock energization of the rotor is started at time T1, the lock energization control circuit 5 outputs a lock energization control signal to the predrive circuit 4, and the predrive circuit 4 performs gate drive based on the lock energization control signal. The signal is output to the inverter circuit 2. As shown in FIG. 4A, in section 1, a pulse signal with an on-duty d1 is input once to the gate terminal of the switching element (U-phase high-side switching element) Q1 of the inverter circuit 2. Then, it is determined whether or not the input time of the pulse signal has reached a predetermined time t0 set in advance (step S12 in FIG. 3). If it is determined that the input time has reached t0, then the on-duty is turned on. Is reached (step S13 in FIG. 3), and if it is determined that the on-duty d1 has not reached the preset maximum value, the next interval 2 is determined. Then, a pulse signal of d2 whose on-duty is larger than d1 is inputted. Then, it is determined whether or not the input time of the pulse signal has reached t0 (step S12 in FIG. 3), and when it is determined that the time has reached t0, the on-duty d2 is set to a preset on-duty maximum value. Is determined (step S13 in FIG. 3), and if it is determined that the on-duty d2 has not reached the preset maximum value, in the next section 3, the on-duty is further increased. The pulse signal d3 is input (step S14 in FIG. 3). Until the on-duty of the pulse signal reaches a preset maximum value, the operation of inputting the pulse signal having an increased on-duty to the switching element Q1 at an interval of a predetermined time t0 is repeated (steps S11 to S14 in FIG. 3). ).

In the present embodiment, as shown in FIG. 4A, in the sections 1 to 7, it is determined that the on-duty of the pulse signal of the switching element Q1 does not reach the preset maximum value d7, and the input time At t0, pulse signals of on-duties d1 to d7 whose on-duty gradually increase are sequentially input. Accordingly, during the period from time T1 to time T2, as shown in FIG. 4B, the lock current Iu flowing through the U-phase drive coil Lu gradually increases to the current value I2.

When the time reaches T2, it is determined that the on-duty of the pulse signal of the switching element Q1 has reached a preset maximum value at the start of the next interval (step S14 in FIG. 3), and the on-duty is fixed to the maximum value. The pulse signal is input, it is determined whether or not the time has reached T3 (step S15 in FIG. 3), and the input time is t0 and the on-duty until it is determined that the time has not reached T3. Is continuously input to the switching element Q1.

In the present embodiment, as shown in FIG. 4A, in the sections 8 to 12, the gate terminal of the switching element Q1 has the input time t0 and the on-duty is set to a preset maximum value d7. A fixed pulse signal is input. Accordingly, during the period from time T2 to time T3, the lock current Iu flowing through the U-phase drive coil Lu becomes a constant current value I2. When the time reaches T3, the lock energization process is terminated.

As shown in FIG. 4A, in the period from time T1 to time T3, switching elements Q2 (U-phase low-side switching elements), Q3 (V-phase high-side switching elements), Q5 (W-phase high-side switching elements). Low level gate drive signals S2, S3, S5 are input to the respective gate terminals of the side switching elements), and the respective gates of the switching elements Q4 (V-phase low-side switching elements) and Q6 (W-phase low-side switching elements). High level gate drive signals S4 and S6 are input to the terminals. As a result, the current Iu flowing through the U-phase drive coil Lu flows to the GND through the drive coil Lv, the switching element Q4, and the resistance element, and flows to the GND through the drive coil Lw, the switching element Q6, and the resistance element.

  The length of the input time t0 and the increase ratio of the on-duty are adjusted according to the motor specifications, etc., so that the degree of inclination at which the lock current increases and the time until the constant current I2 is reached are set appropriately. Is possible.

As described above, in the sensorless synchronous motor drive device 1 according to the present embodiment, the lock output from the lock energization control circuit 5 of the control circuit unit 3 to the predrive circuit 4 in the lock energization process at the start of activation of the synchronous motor 10. Based on the energization control signal, the on-duty of the pulse signal input from the pre-drive circuit 4 to the switching element Q1 of the inverter circuit 2 is gradually increased so that the lock current Iu flowing through the U-phase drive coil Lu is a predetermined value. Since the predetermined period until reaching the value I2 is gradually increased, a large current exceeding the predetermined value I2 does not flow through the U-phase drive coil Lu, and the synchronous motor 10 can be prevented from being stepped out. The rotor can be controlled to reliably stop at a predetermined position.

  As described above, the sensorless synchronous motor drive device 1 according to the present embodiment is configured so that the pre-drive circuit 4 increases so as to increase over a predetermined time until the lock current reaches a predetermined value when the rotor is locked. By providing the control circuit unit 3 with the lock energization control circuit 5 that outputs a control signal at the same time, the rotor can be securely connected during the energization of the lock that locks the rotor at a predetermined position at the start-up while having a simple circuit configuration. It is possible to provide a sensorless synchronous motor driving device that can be controlled to stop at a predetermined position.

  The representative embodiment of the present invention has been described above, but the present invention is not limited to the circuit configuration of the above embodiment, and various modifications can be made without departing from the spirit of the present invention. .

  For example, in the above embodiment, the pulse signal whose on-duty gradually increases is described as being input to the gate terminal of the switching element Q1 (U-phase high-side switching element) of the inverter circuit 2. The control mode by the circuit 5 is not limited to the timing chart shown in FIG. 3, but a pulse signal whose on-duty gradually increases is input to switching elements other than the switching element Q1, and is input to other switching elements. The same effect can be obtained if the gate drive signal to be selected is appropriately selected.

  The above will be specifically described with reference to FIG. FIG. 5 shows a timing chart showing the correlation of drive signal waveforms inputted to the switching elements Q1 to Q6 of the inverter circuit 2 in another control mode by the lock energization control circuit 5.

In FIG. 5, when a pulse signal S2 whose on-duty gradually increases is input to switching element Q2 (U-phase low-side switching element), switching elements Q1 (U-phase high-side switching element) and Q4 (V-phase low-side switching element) Low level gate drive signals S1, S4, S6 are input to the respective gate terminals of the switching elements Q6 (W-phase low-side switching elements), and switching elements Q3 (V-phase high-side switching elements), Q5 (W By inputting the high-level gate drive signals S3 and S5 to the respective gate terminals of the phase high-side switching element), the lock current Iu flowing through the U-phase drive coil Lu can be gradually increased.

  Also, when a pulse signal whose on-duty gradually increases is input to a switching element connected to a drive coil other than the U-phase, for example, the on-duty gradually increases to the switching element Q3 (V-phase high-side switching element). A low level gate at each gate terminal of the switching element Q1 (U-phase high-side switching element), Q4 (V-phase low-side switching element), and Q5 (W-phase high-side switching element). A drive signal is input, and a high-level gate drive signal is input to the respective gate terminals of the switching elements Q2 (U-phase low-side switching element) and Q6 (W-phase low-side switching element), whereby a V-phase drive coil Gradually increasing the lock current flowing in Lv Kill.

  Furthermore, for a set of two switching elements that drive one of the three phases, a pulse signal whose on-duty gradually increases is input to one of the switching elements, and one switching element is input to the other switching element. The same effect can be obtained by a method of inputting a pulse signal in which the on / off operation is opposite to that of the element and the on-duty is gradually decreased. For example, a pulse signal whose ON duty gradually increases is input to the switching element Q1 (U-phase high-side switching element), and the switching element Q1 (ON-phase low-side switching element) is turned on / off with the switching element Q1. On the other hand, a pulse signal whose on-duty gradually decreases is input, and a low-level gate drive signal is input to each gate terminal of switching element Q4 (V-phase low-side switching element) and Q6 (W-phase low-side switching element). Then, by inputting a high level gate drive signal to the gate terminals of the switching elements Q3 (V-phase high-side switching element) and Q5 (W-phase high-side switching element), the U-phase drive coil Lu Gradually increasing the lock current that flows Kill.

In each of the control modes described above, which of the two switching elements connected to each of the other two phases other than the phase to which the switching element that inputs the pulse signal whose on-duty gradually increases is connected is selected. On the other hand, a high-level gate drive signal is input to the switching element on the side opposite to the side (high side or low side) to which the pulse signal with gradually increasing on-duty is input. By controlling in this way, stable lock energization can be achieved.

However, it is not always necessary to input a high-level gate drive signal to one of the two switching elements connected to each of the other two phases, and the switching element of at least one of the two phases. A high-level gate drive signal may be input to one of the two.

  In the above embodiment, the sensorless synchronous motor driving device that drives a three-phase motor having a three-phase driving coil has been described. However, the control target of the sensorless synchronous motor driving device according to the present invention is limited to a three-phase motor. It is not a thing, but it is applicable with respect to the motor provided with the drive coil of two or more phases.

In the above embodiment, the switching element constituting the inverter circuit 2 is described as a MOSFET. However, the present invention is not limited to this, and may be a bipolar transistor, for example.

1: sensorless synchronous motor drive device, 2: inverter circuit, 3: control circuit unit, 4: pre-drive circuit, 5: lock energization control circuit, 6: motor drive control circuit, 10: synchronous motor, Q1, Q3, Q5: High-side switching element (MOSFET), Q2, Q4, Q6: Low-side switching element (MOSFET), Lu: U-phase drive coil, Lv: V-phase drive coil, Lw: W-phase drive coil, Iu: U-phase Lock current flowing in the drive coil, Vcc: DC power supply

Claims (4)

A sensorless synchronous motor drive device having an inverter circuit that selectively energizes the drive coil based on a counter electromotive voltage generated in a plurality of phase drive coils without using a sensor for detecting the position of the rotor,
A pre-drive circuit that outputs a drive signal to the inverter circuit, and the pre-drive circuit so that a lock current for holding the rotor at a predetermined lock position when the motor is started flows from the inverter circuit to the drive coil. A control circuit unit including a lock energization control circuit to control,
The lock energization control circuit outputs a signal to the pre-drive circuit for controlling the lock current to increase over a predetermined time until the lock current reaches a predetermined value. apparatus. The inverter circuit includes a high-side switching element and a low-side switching element provided for each phase so that a driving current flows for each phase of the plurality of phase driving coils, and the adjustment of the magnitude of the lock current is 2. The control circuit according to claim 1, wherein a drive signal input to the high-side switching element and the low-side switching element provided for each phase from the pre-drive circuit is controlled by the lock energization control circuit. Sensorless synchronous motor drive device.   The magnitude of the lock current is adjusted by turning on a pulse signal input from the pre-drive circuit to a high-side switching element and / or a low-side switching element provided in any one of the plurality of driving coils. 3. The sensorless synchronous motor driving apparatus according to claim 2, wherein the driving is performed by varying the duty.   In the pre-drive circuit, an on-duty increases with time until the magnitude of the lock current reaches a predetermined value in a high-side switching element provided in one of the plurality of phase driving coils. A pulse signal is input, a low-level driving signal is input to the low-side switching element provided in the one phase and the high-side switching elements of each phase excluding the one phase, and the low-side switching of each phase excluding the one phase 4. The sensorless synchronous motor driving apparatus according to claim 2, wherein a high level driving signal is input to the element.

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