JP2016192844A - Motor drive control device and motor drive control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To brake a fan motor over a long period when a power supply is turned off.SOLUTION: A motor drive control device comprises: an inverter circuit (16) that has a plurality of switching elements (Q1-Q6) for switching an input voltage (Vin) supplied from a power supply (2), and that outputs a drive signal to a motor (20); a gate driver (12) connected with the inverter circuit (16), and that on/off-controls the plurality of switching elements (Q1-Q6) on the basis of supplied first control signals (UH, UL, VH, VL, WH, WL); a regeneration voltage generation circuit (14) connected with the inverter circuit (16), and that on/off-controls at least some of the plurality of switching elements (Q1-Q6) so that a regeneration voltage to the power supply (2) is generated, on the basis of a supplied second control signal (BR); and a pre-driver (10) that outputs at least one of the first control signals and the second control signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor drive control device and a motor drive control method suitable for cooling electrical equipment.

  In high-availability electrical equipment (hereinafter referred to as “main equipment” in this specification) such as communication equipment of a mobile communication network or server equipment for a data center, it is called a “fan unit” for cooling the enclosure. Things are used. The fan unit is a unit in which a cooling fan and peripheral circuits are combined into a single unit so that the main unit can be hot-plugged. For example, if a fan unit fails, the fan unit can be replaced in a short time while the main unit is operating by pulling out the failed fan unit from the main unit and inserting a spare fan unit into the main unit. can do.

  The fan unit includes a motor that is a permanent magnet type synchronous motor that rotates the fan, and a PWM (Pulse Width Modulation) modulated DC voltage by a switching element such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). An inverter to be applied and a pre-driver that outputs a PWM modulated wave for on / off control of these switching elements are provided. Here, when the DC voltage supplied to the inverter is relatively low, the switching element can be directly driven by the pre-driver.

  When the fan unit is pulled out from the main unit, it may cause an accident if the fan keeps rotating due to inertia, so it is desirable to brake the fan and stop it quickly. In general, short-circuit braking (short brake) is frequently used as a method of braking the fan. In this case, the on / off state of the switching element in the inverter is controlled so that the coils of each phase of the motor are mutually short-circuited, so that the inverter acts as an electromagnetic brake.

  In a state where the fan unit is connected to the main device, a power supply voltage is supplied from the main device to the fan unit. Here, a voltage stabilizing capacitor is connected in parallel to the power supply input terminal of the fan unit, and this capacitor is charged. When the fan unit is pulled out from the main unit, the power supply from the main unit cannot be received. However, since a certain amount of charge remains in the capacitor, the pre-driver etc. is driven by the remaining charge in the capacitor, causing a short circuit. Braking is executed.

  By the way, in recent years, fan units with high input voltage specifications have been required to be smaller, more efficient, and faster. As a method for driving a MOSFET for switching a DC voltage with high efficiency, for example, Patent Document 1 discloses A technique is disclosed in which a gate driver that amplifies the voltage of a PWM signal output from a pre-driver is inserted between the pre-driver and the inverter.

JP 2011-55703 A

However, since the rotational speed of the motor has increased, it is necessary to continue braking for a longer time when the fan unit is pulled out from the main unit. On the other hand, there is a limit to the capacitance of the voltage stabilizing capacitor, and it is becoming difficult to cope with braking for a long time.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a motor drive control device and a motor drive control method capable of braking a motor for a long time.

  In order to solve the above problems, a motor drive control device of the present invention has a plurality of switching elements that switch input voltage supplied from a power supply, and is connected to the inverter circuit that outputs a drive signal to the motor. A gate driver that performs on / off control of the plurality of switching elements based on the supplied first control signal, and a regenerative power source connected to the inverter circuit based on the supplied second control signal. A regenerative voltage generation circuit that performs on / off control of at least some of the plurality of switching elements, and a pre-driver that outputs at least one of the first control signal and the second control signal so that a voltage is generated It is characterized by having.

  According to the motor drive control device of the present invention, the motor can be braked for a long time.

It is a block diagram of the fan unit of one embodiment of the present invention. 4 is a flowchart of a stop control program executed by a pre-driver. It is a wave form diagram of each part in one embodiment and a comparative example. It is a figure which shows the change of the rotational speed in one Embodiment and a comparative example. It is a circuit diagram of the various modifications of a regenerative voltage generation circuit. It is a wave form diagram of each part in the modification of one Embodiment.

[Configuration of the embodiment]
<Overall configuration>
First, the details of the fan unit 100 according to an embodiment of the present invention will be described with reference to FIG.
In FIG. 1, the capacitor 2 is connected between the voltage input terminal of the fan unit 100 and the ground potential, and is charged by a DC voltage of 48 [V] supplied from a main unit (not shown). The terminal voltage of the capacitor 2 is called the input voltage Vin. The regulator circuit unit 4 includes a regulator 4a that generates the power supply voltage VCC1 from the input voltage Vin and a regulator 4b that generates the power supply voltage VCC2 from the power supply voltage VCC1. Here, the power supply voltage VCC1 is 14 [V] when the input voltage Vin is 14 [V] or more, and is equal to the input voltage Vin when the input voltage Vin is less than 14 [V]. The power supply voltage VCC2 is 5 [V] when the power supply voltage VCC1 is 5 [V] or more, and is equal to the power supply voltage VCC1 when the power supply voltage VCC1 is less than 5 [V].

  The motor 20 is a permanent magnet type synchronous motor and has U-phase, V-phase, and W-phase input terminals. U-phase, V-phase, and W-phase motor coils (not shown) are connected between these input terminals and a neutral point (not shown). A rotor (not shown) of the motor 20 has a permanent magnet embedded therein and is driven to rotate by a rotating magnetic field generated by the motor coil. The rotor is coupled to the fan 22 so that the fan 22 is driven to rotate.

  The inverter circuit 16 has switching elements Q1 to Q6. Each switching element Q1 to Q6 is a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and a free-flowing element connected in parallel to each MOSFET. And a diode. An input voltage Vin is applied to the drain terminal of the switching element Q1, and the source terminal of the switching element Q1 and the drain terminal of the switching element Q2 are connected to each other and to the U-phase input terminal of the motor 20. The source terminal of the switching element Q2 is connected to the ground potential.

  The switching elements Q3 and Q4 are connected in series like the switching elements Q1 and Q2. The input voltage Vin is applied to the series circuit, and the connection point of the switching elements Q3 and Q4 is the V-phase input terminal of the motor 20. It is connected to the. The switching elements Q5 and Q6 are also connected in series like the switching elements Q1 and Q2. The input voltage Vin is applied to the series circuit, and the connection point of the switching elements Q5 and Q6 is the W-phase input terminal of the motor 20. It is connected to the.

  The pre-driver 10 is a circuit driven by a power supply voltage VCC1 (maximum 5 [V]), and a capacitor 6 is connected between the voltage input terminal and the ground potential. The pre-driver 10 is configured as a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and various control programs are stored in the ROM. Has been.

  Then, the pre-driver 10 outputs PWM signals UH, UL, VH, VL, WH, WL (first control signals) that specify the on / off states of the switching elements Q1 to Q6 described above according to this control program. . These PWM signals have a level of 0 [V] (off) or 5 [V] (on), but the switching elements Q1 to Q6 are completely turned on at a voltage of 5 [V] in the on state. I can't. That is, since the voltage at the source terminal of the high-side switching elements Q1, Q3, Q5 is higher than 5 [V], the switching elements Q1, Q3, Q5 are turned on at a gate voltage of 5 [V]. It is not possible.

  On the other hand, the low-side switching elements Q2, Q4, and Q6 can be turned on also by a gate voltage of 5 [V]. However, since the on-resistance value is high at a gate voltage of 5 [V], the switching elements Loss at Q2, Q4, and Q6 increases. In order to reduce the loss, it is desirable to further increase the gate voltage. Therefore, a gate driver 12 is provided after the pre-driver 10.

  The gate driver 12 has high-side and low-side drivers (hereinafter simply referred to as drivers) 12U, 12V, and 12W corresponding to the U-phase, V-phase, and W-phase. The driver 12U amplifies the voltage level of the low-side PWM signal UL from 0 [V] (off) to 14 [V] (on), and applies it to the gate terminal of the low-side switching element Q2. Further, the voltage of the high-side PWM signal UH is level-shifted from the reference level +0 [V] (off) to the reference level +14 [V] (on) with the voltage at the source terminal of the switching element Q1 as the reference level. Amplified and applied to the gate terminal of the switching element Q1.

  The drivers 12V and 12W are configured in the same manner as the driver 12U, and drive the low-side switching elements Q4 and Q6 and the high-side switching elements Q3 and Q5, respectively. In this manner, the switching elements Q1 to Q6 are reliably turned on / off by the gate driver 12 in accordance with the PWM signals UH, UL, VH, VL, WH, and WL.

  The resistors 8 a and 8 b divide the input voltage Vin, and the divided voltage CV is supplied to the pre-driver 10. Thereby, the input voltage Vin is monitored by the pre-driver 10. When the input voltage Vin becomes lower than the predetermined voltage threshold Vt, the supply of the PWM signal to the gate driver 12 is stopped, and the control signal BR (second control signal) that is a PWM signal from the pre-driver 10 is regenerated. It is output to the generation circuit 14.

<Regenerative voltage generation circuit 14>
The regenerative voltage generation circuit 14 supplies the control signal BR as control signals S2a and S2b to the gate terminals of the U-phase and V-phase low-side switching elements Q2 and Q4 via the diodes D1 and D2. Here, the function of the regenerative voltage generation circuit 14 will be described. First, if the control signal BR is at a high level (5 [V]), the switching elements Q2 and Q4 are turned on, and the U-phase and V-phase motor coils are switched to the ground potential via the switching elements Q2 and Q4. Current flows. This state is also a state in which a short brake is applied to the motor 20 using U-phase and V-phase motor coils.

  When the control signal BR is set to a low level (0 [V]) in this state, the switching elements Q2 and Q4 are turned off. However, since current continues to flow through the U-phase and V-phase motor coils, the current returns to the capacitor 2 via the return diodes included in the switching elements Q1 and Q3 to charge the capacitor 2. Thus, by alternately repeating the short brake state and the regenerative state, it is possible to continue braking the motor 20 while securing a voltage for operating the pre-driver 10.

[Operation of the embodiment]
Next, the operation of this embodiment will be described.
When the fan unit 100 is pulled out from the main device or when the main device itself is turned off, the power supply from the main device to the fan unit 100 is stopped. When the pre-driver 10 determines that the power supply from the main device has been stopped, the stop control program shown in FIG. 2 is started. In the present embodiment, the voltage at which the driving of the gate driver 12 stops is 14 [V], and this value is described as the voltage threshold Vt.

  In FIG. 2, when the process proceeds to step S2, the level of the input voltage Vin is monitored via the resistors 8a and 8b. Next, when the process proceeds to step S6 (determination process), it is determined whether or not the input voltage Vin is less than the voltage threshold value Vt. In this embodiment, the voltage threshold Vt is a value equal to the power supply voltage VCC1 (= 14 [V]). Immediately after the power supply from the main device is stopped, the input voltage Vin is normally a value in the vicinity of 48 [V]. Therefore, the determination is “No” here, and the process proceeds to step S4 (first control process). )

  In step S4, reverse braking is applied to the motor 20. That is, PWM signals UH, UL, VH, VL, WH, WL (first control signals) are output from the pre-driver 10 so that torque is applied to the motor 20 in the direction opposite to the current rotation direction. The ON / OFF state of the switching elements Q1 to Q6 in the inverter circuit 16 is switched via the gate driver 12.

  Thereafter, the process returns to step S2, and the loop of steps S2, S4, and S6 is repeated until the input voltage Vin becomes less than the voltage threshold value Vt. During that period, the reverse brake is continuously applied to the motor 20, and the rotational speed of the motor 20 decreases rapidly. When the input voltage Vin becomes less than the voltage threshold Vt, “Yes” is determined in step S6, and the process proceeds to step S8 (second control process).

  In step S8, the output of the PWM signal from the pre-driver 10 to the gate driver 12 is stopped. Next, when the process proceeds to step S10, the control signal BR (second control signal) is sent from the pre-driver 10 to the switching elements Q2 and Q4 via the diodes D1 and D2 in the regenerative voltage generation circuit 14. Is output. Thereafter, the control signal BR continues to be output. However, if the rotational speed of the motor 20 decreases over time, the power supply voltage VCC1 at which the pre-driver 10 can operate cannot be secured. Since the operation of the pre-driver 10 is stopped at this time, the processing of this program is also ended. Thereafter, the motor 20 rotates by inertia for a certain period, but eventually stops completely.

Here, FIGS. 3A to 3C show waveform diagrams of the respective units during execution of the above-described stop control program (FIG. 2). In the present embodiment, as in the description of FIG. 2, the voltage at which the driving of the gate driver 12 stops is 14 [V], and this value is described as the voltage threshold Vt.
The input voltage Vin shown in FIG. 3 (a) continues to decrease as power supply from the main device stops, and reaches the power supply voltage VCC1 (= voltage threshold Vt) at time t10. In the present embodiment, before time t10, the reverse brake is continuously applied to the motor 20 by the process of step S4 in FIG. Therefore, during this period, as shown in FIG. 3B, the pre-driver 10 continues to output the PWM signal UH (first control signal). FIG. 3B shows only the PWM signal UH, but the other PWM signals UL, VH, VL, WH, WL continue to be output within the same period.

  When the input voltage Vin reaches the power supply voltage VCC1 (= voltage threshold Vt) at time t10, the output of the PWM signal from the pre-driver 10 to the gate driver 12 is stopped (step S8), and FIG. As shown, a control signal BR, which is a PWM signal, is directly supplied from the pre-driver 10 to the switching elements Q2 and Q4.

  By supplying the control signal BR to the switching elements Q2 and Q4, the short brake state and the regenerative state are alternately repeated for the U phase and the V phase of the motor 20, but the input voltage Vin is at time t10. It continues to decline after that. At time t14, the input voltage Vin reaches the power supply voltage VCC2 (= 5 [V]) of the pre-driver 10. However, since the pre-driver 10 can continue to operate even if the power supply voltage VCC2 slightly falls below 5 [V], it continues to output the control signal BR after time t14. However, at time t15, since the input voltage Vin becomes too low and the pre-driver 10 becomes inoperable, the output of the control signal BR is also stopped.

[Comparative example]
Next, in order to clarify the effect of the present embodiment, a comparative example will be described.
Although the configuration and operation of the comparative example are the same as those of the above-described embodiment, the control signal BR is not a PWM signal, and is maintained at a high level (5 [V]) as shown in FIG. Is different. When the control signal BR is kept at the high level, power cannot be regenerated through the U phase and the V phase, so that the slope of the input voltage Vin after time t10 is as shown in FIG. It is larger than the embodiment (FIG. 3A).

  Therefore, the time t12 at which the input voltage Vin reaches the power supply voltage VCC2 (= 5 [V]) is earlier than the time t14 in the above embodiment, and the time t13 at which the output of the control signal BR is stopped is also implemented. It is earlier than time t15 in the embodiment. Thereby, in this comparative example, it turns out that braking of the motor 20 cannot be continued over a long time.

  Moreover, the rotational speed of the motor 20 in the said embodiment and a comparative example is shown in FIG. In FIG. 4, a characteristic A is the above embodiment, and a characteristic B is that of a comparative example. In FIG. 4, it is assumed that the motor 20 is normally operating from time t0 to t2, and the power supply from the main unit to the fan unit 100 is stopped at time t2. During the period from time t2 to time t10, the rotation speed is reduced by the reverse brake, and after time t10, the motor 20 is braked by the control signal BR. According to the characteristic A of the above embodiment, the time t20 at which the motor 20 is completely stopped is earlier than the time t21 at which the motor 20 is completely stopped by the characteristic B of the comparative example.

[Modification]
The present invention is not limited to the above-described embodiments, and various modifications can be made. The above-described embodiments are illustrated for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Further, it is possible to delete a part of the configuration of each embodiment, or to add or replace another configuration. Examples of possible modifications to the above embodiment are as follows.

(1) The combination of the two phases to which the regenerative voltage generation circuit 14 is connected is not limited to that of the embodiment (U phase, V phase), and may be any two phases. That is, the switching elements that supply the control signal BR are not limited to the U-phase and V-phase switching elements Q2 and Q4, but any two of the U-phase, V-phase, and W-phase switching elements Q2, Q4, and Q6. It may be a switching element.

(2) Instead of the regenerative voltage generation circuit 14 shown in FIG. 1, the regenerative voltage generation circuits 14a to 14f shown in FIGS. 5 (a) to 5 (f) may be applied.
In the regenerative voltage generation circuit 14a shown in FIG. 5A, different control signals BR1 and BR2 (second control signals) are supplied to the diodes D1 and D2. Here, for example, the control signals BR1 and BR2 are both square waves having a duty ratio of 50%, and may be signals in which the on / off state is inverted. Thereby, the short brake state and regenerative state of switching element Q2, Q4 can be switched complementarily.

  Further, in the regenerative voltage generation circuit 14b shown in FIG. 5B, compared to the regenerative voltage generation circuit 14 shown in FIG. 1, the switching element Q11 and the resistor R1 are inserted before the diodes D1 and D2. Then, the current of the control signal BR is amplified by the switching element Q11, and the current-amplified control signal BR is output to the resistor R1. Thereby, the switching speed of switching element Q2, Q4 can be made faster, and the loss in switching element Q2, Q4 can be reduced.

  Further, the regenerative voltage generating circuit 14c shown in FIG. 5C is different from the regenerative voltage generating circuit 14a shown in FIG. 5A in that the switching elements Q11 and Q12 and the resistors R1 and R1 are arranged in front of the diodes D1 and D2. R2 is inserted, and the control signals BR1 and BR2 are current-amplified by these. Therefore, similarly to the circuit of FIG. 5B, the loss in the switching elements Q2 and Q4 can be reduced.

  In the regenerative voltage generation circuit 14d shown in FIG. 5D, the control signal BR is output as control signals S2a, S2b, and S2c via the diodes D1 to D3. These control signals S2a, S2b, and S2c are supplied to the gate terminals of U-phase, V-phase, and W-phase low-side switching elements Q2, Q4, and Q6. Thereby, the short brake state and the regenerative state can be alternately repeated for all phases of the U phase, the V phase, and the W phase.

  Note that when such control is applied to only two phases of the U phase, V phase, and W phase (FIGS. 1 and 5A to 5C), it is applied to all phases of the U phase, V phase, and W phase. Which case (this modified example) is advantageous depends on conditions such as internal resistance of each part of the fan unit 100.

  In addition, when the short brake state and the regenerative state are alternately repeated for all phases of the U phase, the V phase, and the W phase, two types of control signals BR1 and BR2 are used as shown in FIG. Can do. As described with reference to FIG. 5A, the control signals BR1 and BR2 are, for example, square waves with a duty ratio of 50%, and may be signals with the on / off state inverted. In the example of FIG. 5E, the control signal BR1 is supplied to the switching elements Q2 and Q4 as U-phase and V-phase control signals S2a and S2b via the diodes D1 and D2, and the control signal BR2 is supplied to the diode D3. Is supplied to the switching element Q6 as a W-phase control signal S2c.

  Further, when the short brake state and the regenerative state are alternately repeated for all phases of the U phase, the V phase, and the W phase, as shown in FIG. 5F, three types of control signals BR1 to BR3 (second Control signal) can be used. The control signals BR1 to BR3 are preferably square waves having a duty ratio of 50%, for example, and may be signals having phases different from each other by 120 °. In the example of FIG. 5 (f), the control signals BR1 to BR3 are sent to the switching elements Q2, Q4 and Q6 as the U-phase, V-phase and W-phase control signals S2a, S2b and S2c via the diodes D1 to D3. Supplied.

  Further, with respect to the configuration of FIGS. 5D to 5F, for each control signal BR, BR1 to BR3, the switching elements and resistors similar to the switching element Q11 and the resistor R1 shown in FIG. A controller may be inserted to amplify the current of these control signals BR and BR1 to BR3. Further, in any of the above embodiments and the modified examples of FIGS. 5A to 5F, the duty ratio of the control signals BR and BR1 to BR3 which are the second control signals is not limited to 50%, and the frequency is also set. It is not limited. Further, the duty ratio and the frequency may be changed with time.

(3) In the above embodiment, the voltage threshold Vt used in step S6 (determination process) in FIG. 2 is (= 14 [V]) of the power supply voltage VCC1. However, the voltage threshold Vt may be any value appropriate for use in the determination. For example, the voltage threshold Vt may be a value lower than 14 [V]. This is because the gate driver 12 can operate even if the power supply voltage VCC1 is slightly lower than 14 [V]. Examples of waveforms of the input voltage Vin, the power supply voltage VCC1, the PWM signal UH, and the control signal BR when the voltage threshold Vt is lower than 14 [V] are shown in FIGS. 6A to 6D, it is assumed that the power supply from the main device to the fan unit 100 is stopped at time t2.

  At time t10, the input voltage Vin reaches the power supply voltage VCC1 (14 [V]), but the PWM signal UH continues to be output. The same applies to PWM signals UL, VH, VL, WH, WL (first control signals) (not shown). Then, at time t31 when the input voltage Vin reaches the voltage threshold Vt, the output of the PWM signal UH and the like is stopped, and the output of the control signal BR (second control signal) is started. According to this modification, it is possible to secure a longer time for applying the reverse brake by the PWM signal UH or the like than in the above embodiment, and further reduce the rotational speed of the motor 20 at the timing immediately before the control signal BR is output. be able to.

(4) In the above embodiment, the input voltage Vin is monitored in step S6 (determination process) in FIG. 2, but in step S6, instead of monitoring the input voltage Vin, the supply voltage (power supply voltage) to the gate driver 12 is monitored. VCC1) may be monitored.

(5) Further, the monitoring target in step S6 of FIG. 2 is not limited to the voltage, and may be an elapsed time after the voltage such as the input voltage Vin or the power supply voltage VCC1 becomes equal to or lower than a predetermined value. This is because the timing at which the input voltage Vin or the like becomes the voltage threshold Vt can be inferred from the elapsed time. Further, the monitoring target in step S <b> 6 may be the rotation speed of the motor 20. This is because the timing at which the input voltage Vin or the like becomes the voltage threshold Vt can be estimated from the rotation speed. In addition, parameters other than the elapsed time and the rotation speed may be monitored as long as the input voltage Vin can be analogized.

(6) The flowchart shown in FIG. 2 is a specific example, and the processing content is not limited to this flowchart. For example, another process may be inserted between the steps in FIG.

(7) In the above embodiment, the motor 20 is a three-phase permanent magnet type synchronous motor. However, since the type and the number of phases of the motor 20 may be appropriate depending on the application, the above embodiment is used. It is not limited to those.

(8) In the embodiment described above, the pre-driver 10 outputs the second control signal after stopping the output of the first control signal. However, the pre-driver 10 has a condition that the power supply voltage VCC1 has reached a voltage value that can drive the gate driver 12 (in other words, no signal is output from the gate driver 12 to the switching elements Q1 to Q6). If the output of the second control signal is started, the output of the first control signal can be continued without stopping.

(9) In the above embodiment, an example in which PWM signals UH, UL, VH, VL, WH, and WL for applying reverse braking to the motor 20 are applied as the first control signal output in step S6 of FIG. Explained. However, the first control signal is not limited to the one that applies reverse braking, and may be PWM signals UL, VL, WL (or two-phase signals among them) that apply short braking.

[Overview of composition and effect]
As described above, the fan unit 100 of the above embodiment has a plurality of switching elements (Q1 to Q6) for switching the input voltage (Vin) supplied from the power supply (2), and is driven by the motor (20). An inverter circuit (16) that outputs a signal and a plurality of switching elements (UH, UL, VH, VL, WH, WL) connected to the inverter circuit (16) and based on the supplied first control signals (UH, UL, VH, VL, WH, WL) The regenerative voltage for the power source (2) is connected to the gate driver (12) that performs on / off control of Q1 to Q6) and the second control signal (BR) that is connected to the inverter circuit (16). A regenerative voltage generation circuit (14) that performs on / off control of at least a part of the plurality of switching elements (Q1 to Q6) and a first control signal (UH, L, is VH, VL, WH, characterized in that it has a pre-driver (10) for outputting at least one of WL) or the second control signal (BR).

  Thereby, the pre-driver (10) can apply strong braking to the motor (20) by outputting the first control signals (UH, UL, VH, VL, WH, WL), and the second By outputting the control signal (BR), the motor (20) is braked while generating a regenerative voltage for the power source (2), so that the motor (20) can be continuously braked for a long time.

  Further, the pre-driver (10) outputs a second control signal (BR) to the regenerative voltage generation circuit (14) when the input voltage (Vin) is equal to or higher than a predetermined voltage threshold (Vt). If the first control signal (UH, UL, VH, VL, WH, WL) is output to the gate driver (12) without the input voltage (Vin) being less than the voltage threshold (Vt), the gate The second control signal (BR) is output to the regenerative voltage generation circuit (14) without outputting the first control signal (UH, UL, VH, VL, WH, WL) to the driver (12). It is a thing to do.

  Thereby, the pre-driver (10) outputs the second control signal (BR) to the regenerative voltage generation circuit (14) when the input voltage (Vin) is equal to or higher than the predetermined voltage threshold (Vt). Since the first control signals (UH, UL, VH, VL, WH, WL) are output to the gate driver (12) without any problems, strong braking can be applied to the motor (20). Further, when the input voltage (Vin) is less than the voltage threshold value (Vt), the pre-driver (10) sends the first control signals (UH, UL, VH, VL, WH, By outputting the second control signal (BR) to the regenerative voltage generation circuit (14) without outputting WL), the motor (20) is braked while generating the regenerative voltage for the power supply (2). The motor (20) can be braked for a long time.

  Furthermore, the inverter circuit (16) outputs a three-phase drive signal to the motor (20), and the plurality of switching elements (Q1 to Q6) are high-side and low-side switching elements in each of the three phases. The second control signal (BR) designates an on / off state of at least two-phase low-side switching elements (Q2, Q4) among the three phases. Thus, the inverter circuit (16) can be directly controlled by the pre-driver (10) having a low voltage level.

  Further, in the above embodiment and the modification shown in FIGS. 5B, 5D, and 5E, the regenerative voltage generation circuit (14, 14b, 14d, 14e) includes at least a two-phase low-side switching element (Q2). , Q4) having at least one diode (D1, D2) connected to each of them, and the pre-driver (10) for at least one diode (D1, D2) connected to each phase, A common second control signal (BR) is output. Thereby, the on / off states of the two-phase low-side switching elements (Q2, Q4) can be controlled simultaneously.

  5A, 5C, and 5F, the regenerative voltage generation circuit (14, 14b, 14d, 14e) includes at least two-phase low-side switching elements (Q2, Q4). Each of which has at least one diode (D1, D2) connected to each other, and the pre-driver (10) is different from the at least one diode (D1, D2) connected to each phase. Control signals (BR1, BR2) are output. Thereby, the on / off states of the two-phase low-side switching elements (Q2, Q4) can be controlled independently.

  In the modification shown in FIGS. 5B and 5C, the regenerative voltage generation circuit (14b, 14c) has a second control signal (BR, BR1) in front of at least one diode (D1, D2). , BR2) is further provided with a switching element (Q11, Q12) for amplifying the current of BR2. Thereby, the switching speed of switching element Q2, Q4 can be made faster, and the loss in switching element Q2, Q4 can be reduced.

2 Capacitor (power supply)
4 Regulator circuit unit 4a, 4b Regulator 6 Capacitor 8a, 8b Resistor 10 Pre-driver 12 Gate driver 12U, 12V, 12W High side low side driver 14, 14a-14f Regenerative voltage generation circuit 16 Inverter circuit 20 Motor 22 Fan 100 Fan Unit BR, BR1 to BR3 Control signal (second control signal)
D1-D3 Diodes S2a, S2b, S2c Control signals Q1-Q6, Q11, Q12 Switching element Vin Input voltage Vt Voltage threshold VCC1, VCC2 Power supply voltage UH, UL, VH, VL, WH, WL PWM signal (first control signal )

Claims (7)

An inverter circuit having a plurality of switching elements for switching an input voltage supplied from a power supply and outputting a drive signal to the motor;
A gate driver connected to the inverter circuit and performing on / off control of the plurality of switching elements based on a supplied first control signal;
A regenerative voltage that is connected to the inverter circuit and performs on / off control of at least a part of the plurality of switching elements so that a regenerative voltage for the power supply is generated based on the supplied second control signal. A generation circuit;
A motor drive control device comprising: a pre-driver that outputs at least one of the first control signal and the second control signal. The pre-driver outputs the first control signal to the gate driver without outputting the second control signal to the regenerative voltage generation circuit when the input voltage is equal to or higher than a predetermined voltage threshold. When the input voltage is less than the voltage threshold, the second control signal is output to the regenerative voltage generation circuit without outputting the first control signal to the gate driver. The motor drive control device according to claim 1, wherein the motor drive control device is an output device. The inverter circuit outputs a three-phase drive signal to the motor, and the plurality of switching elements have high-side and low-side switching elements in each of the three-phase phases, and the second The motor drive control device according to claim 2, wherein the control signal designates an on / off state of a low-side switching element of at least two phases of the three phases. The regenerative voltage generation circuit has at least one diode connected to each of the switching elements on at least two phases of the low side,
4. The motor drive control device according to claim 3, wherein the pre-driver outputs the common second control signal to the at least one diode connected to each phase. 5. The regenerative voltage generation circuit has at least one diode connected to each of the switching elements on at least two phases of the low side,
The motor drive control device according to claim 3, wherein the pre-driver outputs different second control signals to the at least one diode connected to each phase. 6. The motor drive control device according to claim 4, wherein the regenerative voltage generation circuit further includes a switching element that amplifies the current of the second control signal before the at least one diode. An inverter circuit having a plurality of switching elements for switching an input voltage supplied from a power supply and outputting a drive signal to the motor;
A gate driver connected to the inverter circuit and performing on / off control of the plurality of switching elements based on a supplied first control signal;
Regenerative voltage generation for performing on / off control of a part of the plurality of switching elements so that a regenerative voltage for the power supply is generated based on a supplied second control signal connected to the inverter circuit Circuit,
A motor drive control method for controlling the motor using a motor drive control device having a pre-driver, and for the pre-driver,
A determination process for determining whether the input voltage is equal to or higher than a predetermined voltage threshold;
When the determination result in the determination process is affirmative, the first control signal is output to the gate driver without outputting the second control signal to the regenerative voltage generation circuit. 1 control process,
When the determination result in the determination process is negative, the second control signal is output to the regenerative voltage generation circuit without outputting the first control signal to the gate driver. The control process of
The motor drive control method characterized by performing this.

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