JP5034229B2 - In-vehicle motor control device, electric power steering device and electric brake device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle motor controller capable of acquiring high output by reducing switching loss, and a power steering apparatus and a motor-driven braking apparatus using the same. <P>SOLUTION: The controller is provided with a voltage booster means 2 for boosting a power source voltage to be output from a DC power source; a motor driving means 4 for driving and controlling a polyphase motor with a pulsewidth modulation signal on the basis of the boosted voltage to be output from the voltage booster means 2; and a voltage boosting control means 5 for detecting a reflux timing of the motor driving means 4 and performing switching control of the voltage booster means at the detected reflux timing. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to an in-vehicle motor control device driven by electric power of a battery mounted on a vehicle, an electric power steering device using the same, and an electric brake device.

  Generally, in-vehicle motor control devices that use a battery as a power source to control energization of an in-vehicle motor are often used in vehicles. For example, in an electric power steering device, conventionally, a steering torque applied to a steering wheel by a driver is detected by a torque sensor, and the motor is driven by pulse width modulation (PWM) control in accordance with the detected torque. Give steering assist force.

  In recent years, it is desired to mount an electric power steering device not only on a small vehicle but also on a medium-sized vehicle and a large vehicle, and the capacity of a motor and its control device has been increased. It has been proposed to adopt a brushless motor instead of a brushed motor with a current restriction by a brush for the motor, and to obtain a higher output by installing a boosting function for the control device.

As a conventional example of an in-vehicle motor control device having a boosting function, for example, a battery voltage output from a battery is boosted by a boosting circuit and supplied to a motor driving circuit. And a switching element composed of a field effect transistor interposed between the other end side of the reactor and the negative electrode side of the battery, and an anode connected to a connection point between the reactor and the switching element It is known that it is composed of a diode and a charge / discharge capacitor inserted between the cathode side of this diode and the negative side of the battery, and adopts a chopper method for supplying an on / off signal to the gate of the switching element. (For example, refer to Patent Document 1).
Japanese Patent Laying-Open No. 2003-200845 (first page, FIG. 6)

However, in the conventional example described in Patent Document 1, the driving voltage of the motor can be increased by boosting the battery voltage with the boosting circuit and supplying the boosted voltage to the motor driving circuit. In this step-up, the switching element is driven by the on / off signal shown in FIG. 15A, so that the source-drain voltage of the switching element is zero and the battery voltage as shown in FIG. 15B. Repeat alternately. At this time, as shown in FIG. 15C, the current flowing through the reactor increases when the switching element is in the on state, and the current _IL increases in this state. The energy accumulated in the capacitor charges the charging / discharging capacitor via the diode, and a high voltage is accumulated in the charging / discharging capacitor.

However, in the above conventional example, switching loss and steady loss occur in the switching element as shown in FIG. When the switching element is turned on / off, a large switching loss occurs as shown in FIG. This switching loss is represented by the product of the drain-source voltage V _DS and the drain current I _D during a transient state when the switching element is turned on and off.

The drain current _{ID at} this time rises steeply from zero when the switching element is inverted from the OFF state to the ON state as shown by the one-dot chain line in FIG. When reversed to the off state, it drops sharply and becomes zero. On the other hand, the source-drain voltage V _DS of the switching element is a switching element opposite to the drain current I _D as shown by the solid line shown in FIG. 16 (a) is from the off-state voltage V _DS Invert the ON state is zero near the This state continues while the switching element is kept on, and when the switching element is reversed from the on state to the off state, it suddenly increases to the boost voltage, and then the boost voltage is maintained. When the state is reversed from the off state to the on state, the value rapidly decreases to a value near zero. For this reason, the switching loss is a value that cannot be ignored as compared with the steady loss, as shown in FIG.

  In order to reduce this switching loss, it is conceivable to suppress the switching by reducing the boosted voltage of the booster circuit when the motor is in a low load state. Response time until the boost voltage reaches the target value occurs, and smooth torque characteristics cannot be obtained, and in order to increase the boost voltage in an emergency, the capacity of the boost circuit must be increased. There is an unsolved problem that excessive battery current is generated.

Moreover, since the switching loss is proportional to the battery current and the boosted voltage, when a large torque is required and a large amount of power needs to be supplied to the motor, the switching loss tends to increase rapidly. This results in an increase in battery voltage.
As described above, according to the conventional example, although the battery output is increased due to the switching loss of the chopper method, the effect of improving the motor output is small, the heat generation of the control device is increased, and the radiator is required to be enlarged. There is.
Accordingly, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and can be used for a vehicle-mounted motor control device that can significantly reduce switching loss, an electric power steering device using the same, and an electric motor It aims to provide a braking device.

In order to achieve the above object, an on-vehicle motor control device according to claim 1 includes a booster that boosts a power supply voltage output from a DC power supply, and a multiphase motor based on the boosted voltage output from the booster. Motor driving means for driving and controlling with a pulse width modulation signal; and boosting control means for detecting the reflux timing of the motor driving means and performing switching control of the boosting means at the detected reflux timing; A reactor having one end connected to the positive electrode side of a DC power source, a diode connected in the forward direction to the other end of the reactor , a charge / discharge capacitor connected to the output side of the diode, the diode and the charge / discharge A first switching element connected in parallel with a capacitor, a connection point between the first switching element and the charge / discharge capacitor, and the DC power supply The second switching element connected to the pole side, the connection point of the diode and the capacitor for charging / discharging, and the connection point of the second switching element and the negative electrode side of the DC power source. A booster having an output terminal to the motor drive circuit, wherein the booster control means turns on the first switching element and turns off the second switching element when the return timing is not detected. To control the accumulated voltage of the charging / discharging capacitor to a motor drive means that is superimposed on the DC power supply voltage input through the reactor, and when the start of the reflux timing is detected, The first switching element is turned off and then the second switching element is turned on to charge a power supply voltage to the charge / discharge capacitor, When serial reflux timing is completed, the on-state the first switching element a second switching element from an off-state is characterized by performing boost control to return to the boosted voltage supply state.

Furthermore, in the control device for a vehicle-mounted motor according to claim 2 , in the invention of claim 1 , the step-up control means includes low output detection means for detecting a low output state of the multiphase motor. When the low output state of the multiphase motor is detected by the output detection means, the first switching element is turned off and the second switching element is controlled to be turned on so that the charging / discharging capacitor is charged. It is characterized by being configured to stop the discharge.

Still further, in the in-vehicle motor control device according to claim 3 , in the invention according to claim 1 or 2 , the boost control unit is configured to control the high side side and the low side side based on a pulse width modulation signal of the motor driving unit. It is characterized in that any one of the switching elements is turned on to detect the return timing.

The electric power steering apparatus according to 請 Motomeko 4 is characterized in that mounting the car motor control apparatus according to any one of claims 1 to 3.
Furthermore, an electric brake device according to a fifth aspect is characterized in that the on-vehicle motor control device according to any one of the first to third aspects is mounted.

  According to the first aspect of the invention, since the switching element of the booster circuit is switched when the motor drive circuit is in the reflux state, the power supply current of the motor drive circuit at this time becomes substantially zero, and at the time of switching of the booster circuit The current flowing through the switching element and the voltage between the terminals can be suppressed to a small level, and the switching loss represented by the product of these currents and the voltage between the terminals can be significantly reduced as compared with the conventional example described above. Can be effectively used to improve motor torque.

According to the first aspect of the present invention, when the motor drive circuit is not in the reflux state, the second switching element is turned off and the first switching element is turned on, whereby the charge / discharge capacitor The boosted voltage obtained by adding the charging voltage stored in the battery voltage to the battery voltage supplied through the reactor can be supplied to the motor drive circuit. When the motor drive circuit enters the reflux state from this state, the first voltage The switching element is turned off, the second switching element is turned on, the charging / discharging capacitor is turned on, and then the second switching element is turned off, so that the charging / discharging capacitor is charged. When the first switching element is turned on, the boosting state can be restored. Since the switching operation of the first and second switching elements is performed when the motor drive circuit is in the reflux state, the current passing through the first switching element is large although the voltage between the terminals is large when the first switching element is turned on / off. Therefore, the switching loss can be reduced. When the second switching element is turned on / off, the current flowing through the second switching element is increased, but the voltage between the terminals is reduced. The effect that it can suppress reliably is acquired.

According to the second aspect of the present invention, when the motor load is in a low load state, the charge / discharge capacitor is provided by turning off the first switching element and turning on the second switching element. The effect that the charging / discharging can be stopped and the life of the charging / discharging capacitor can be extended is obtained. Moreover, when the low load state is changed to the high load state, the boost voltage can be instantaneously obtained by turning on the first switching element and turning off the second switching element. An effect is obtained.

Furthermore, according to the invention of claim 3 , since the reflux timing detection means detects the reflux timing based on the pulse width modulation signal of the motor drive means, the reflux timing can be accurately detected with a simple configuration. effect Ru obtained that.

According to the fourth aspect of the present invention, it is possible to provide a high-output electric power steering device that can reduce the switching loss and can effectively use the battery current as the boosted voltage. At the time of steering, there is an effect that an on-vehicle motor that generates a steering assist force can be driven quickly with high responsiveness.
Furthermore, according to the invention according to claim 5 , it is possible to provide an electric brake device that can reduce the switching loss and can effectively use the battery current for the boosted voltage. The vehicle-mounted motor that operates the electric brake can be driven quickly with high responsiveness.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration in the first embodiment when the present invention is applied to an electric power steering apparatus. In the figure, reference numeral 1 denotes a battery as a DC power supply having a rated voltage of 12 V mounted on a normal vehicle, and the battery power output from the battery 1 is used as boosting means disposed in the vicinity of the battery 1. The boosted output boosted by the booster circuit 2 and supplied to the booster circuit 2 is input to the motor drive circuit 4 disposed in the vicinity of the vehicle-mounted motor 3 that generates the steering assist force. The motor drive circuit 4 is supplied with the battery power of the battery 1 as control power.

  Here, the in-vehicle motor 3 is constituted by a brushless motor driven by three-phase alternating current, and operates as a steering assist force generating motor that generates a steering assist torque of the electric power steering apparatus. The in-vehicle motor 3 is coupled to a steering shaft 7 to which a steering wheel 6 is connected via a speed reduction mechanism 8, the steering shaft 7 is coupled to a rack and pinion mechanism 9, and the rack and pinion mechanism 9 is coupled to a tie rod or the like. It is connected to the left and right steered wheels 11 via a mechanism 10.

  The steering shaft 7 is provided with a steering torque sensor 12 that detects the steering torque input to the steering wheel 6, and the vehicle-mounted motor 3 is provided with a resolver 13 that detects a motor rotation angle. The steering torque detection signal detected by the steering torque sensor 12 and the motor rotation angle detection signal detected by the resolver 13 are input to the motor drive circuit 4.

As shown in FIG. 2, the booster circuit 2 includes input terminals 20p and 20n connected to the positive terminal 1p and the negative terminal 1n of the battery 1, and a positive line 21p and a negative line 21n connected to the input terminals 20p and 20n. Output terminals 22p and 22n connected to each other.
A reactor L1 and a forward diode D1 are connected in series with the positive electrode line 21p. A smoothing capacitor C1 is interposed between the reactor L1 and the negative electrode line 21n, and a charge / discharge capacitor C2 and a field effect transistor as a second switching element are interposed between the cathode of the diode D1 and the negative electrode line 21n. An FET 2 is inserted in series, and a field effect transistor FET 2 as a first switching element is inserted between a connection point of the reactor L 1 and the diode D 1 and a connection point of the charge / discharge capacitor C 2 and the field effect transistor FET 2. Yes.

The gate pulses PG1 and PG2 output from the boost control circuit 5 as the boost control means are supplied to the gates of the field effect transistors FET1 and FET2.
As shown in FIG. 2, the motor drive circuit 4 has input terminals 40p and 40n connected to the output terminals 22p and 22n of the booster circuit 2, and an inverter circuit 41 is connected to the input terminals 40p and 40n.

  The inverter circuit 41 includes a series circuit of field effect transistors FETu and FETu ′ inserted in series between the input terminals 40p and 40n, a series circuit of field effect transistors FETv and FETv ′ connected in parallel with the series circuit, and this circuit. A series circuit of field effect transistors FETw and FETw ′ connected in parallel with the series circuit has a three-phase bridge circuit configuration. Motor output terminals 43u, 43v, and 43w are derived from the connection points of the field effect transistors FETu and FETu ′ and the connection points of the field effect transistors FETv and FETv ′ and the field effect transistors FETw and FETw ′, respectively, of each series circuit. Output terminals 43u, 43b, and 43w are connected to connection points u, v, and w of the excitation windings Lu, Lv, and Lw of the in-vehicle motor 3 that are Δ-connected.

Further, a gate drive circuit 45 for supplying an on / off signal to the gates of the field effect transistors FETu to FETw and FETu ′ to FETw ′ constituting the inverter circuit 41 is provided. The gate drive circuit 45 is provided with pulse width modulation (PWM). ) A microcomputer 46 for outputting signals is provided.
In the microcomputer 46, current detection signals Imu and Imw of current detection circuits 47u and 47w for detecting motor currents at the output terminals 43u and 43w are input to an A / D conversion input terminal. Further, the steering torque signal detected by the steering torque sensor 12 is input to the microcomputer 46, and the steering torque detection signal T from the torque detection circuit 48 that detects the steering torque based on this is input to the A / D conversion input terminal. A motor rotation angle signal θ _M from the motor rotation angle detection circuit 49 that outputs the motor rotation angle signal to which the output signal of the resolver 13 is input is input to the input terminal, and further a vehicle speed sensor 50 that detects the vehicle speed. The vehicle speed detection signal output from is input.

Here, the motor rotation angle detection circuit 49 supplies the excitation signal to the resolver 13, receives the cosine and sine wave signals output from the resolver 13, detects the motor rotation angle based on these signals, and detects the motor rotation angle. Is converted into a digital value, and a 12-bit digital signal is supplied to the input terminal of the microcomputer 46.
Then, the microcomputer 46 executes the steering assist control process shown in FIG.

  As shown in FIG. 3, the steering assist control process first reads the phase currents Imu and Imw output to the in-vehicle motor 3 detected by the current detection circuits 47u and 47w in step S1, and then proceeds to step S2. The phase current Imv is calculated based on the read phase currents Imu and Imw, and then the process proceeds to step S3, where the steering torque T detected by the torque detection circuit 48 and the vehicle speed Vs detected by the vehicle speed sensor 50 are read. To step S4.

In this step S4, the steering assist command value I _M ^* represented by the motor command current value is calculated with reference to the steering assist command value calculation map shown in FIG. 7 based on the read steering torque Ts and vehicle speed Vs. .
Here, as shown in FIG. 4, in the steering assist command value calculation map, the horizontal axis represents the steering torque detection value T, the vertical axis represents the steering assist command value I _M ^* , and the vehicle speed detection value Vs is used as a parameter. A straight line portion L1 that is configured by a characteristic diagram and extends with a relatively gentle gradient regardless of the vehicle speed detection value Vs until the steering torque Ts increases in the positive direction from “0” and reaches the first set value Ts1. When the steering torque Ts increases from the first set value Ts1, the linear portions L2 and L3 that extend with a relatively gentle gradient and the steering torque detection value Ts are the first in the state where the vehicle speed detection value Vs is relatively fast. Straight line portions L4 and L5 that are parallel to the horizontal axis in the vicinity of the second set value Ts2 that is larger than the set value Ts1 of 1, and in a state where the vehicle speed detection value Vs is slow, the straight line portions L6 and L7 having a relatively large gradient; Gradient from these straight lines L6 and L7 Four characteristics composed of straight line portions L8 and L9 having a large slope, a straight line portion L10 having a larger gradient than the straight line portion L8, and straight line portions L11 and L12 extending in parallel with the horizontal axis from the ends of the straight line portions L9 and L10. Similarly, when the steering torque Ts increases in the negative direction, four characteristic lines to be pointed are formed with the above and the origin in between.

Next, the process proceeds to step S5, where the motor rotation angle θ _M detected by the motor rotation angle detection circuit 49 is read. Then, the process proceeds to step S6, where the steering assist command value I _M ^* calculated in step S4 and the motor rotation angle are read. Based on θ _M , three-phase phase separation processing for converting the target phase current values Imu ^* , Imv ^*, and Imw ^* of the U-phase, V-phase, and W-phase of the vehicle-mounted motor 3 is performed, and the process proceeds to step S7.

In step S7, based on the motor phase currents Imu and Imw read in step S1, the motor phase current Imv calculated in step S2, and the target phase current values Imu ^* , Imv ^* and Imw ^* converted in step S6. A PID process is performed on the deviation between the two to perform a current feedback process for calculating the current command values Iut, Ivt and Iwt, and then the process proceeds to step S8 to correspond to the calculated current command values Iut, Ivt and Iwt of each phase. A pulse width modulation (PWM) signal is formed and output to the gate drive circuit 45, and the process returns to step S1.

  As shown in FIG. 2, the boost control circuit 5 receives pulse width modulation signals PWMu to PWMw for the high-side field effect transistors FETu to FETw of the inverter circuit 41 output from the microcomputer 46 to the gate drive circuit 45. AND gate 51, AND gate 52 to which pulse width modulation signals PWMu 'to PWMw' are input to the low-side field effect transistors FETu 'to FETw' of inverter circuit 41, and outputs of both AND gates 51 and 52 are input. OR gate 53 and an inverter 54 that inverts the output of the OR gate 53, and outputs a gate pulse PG1 supplied from the inverter 54 to the gate of the field effect transistor FET1 as the first switching element of the booster circuit 3. , Orage The second gate pulse PG2 supplied to the gate of the field effect transistor FET2 as a switching element of the step-up circuit 3 from preparative 53 is output. These gate pulses PG1 and PG2 are supplied to the field effect transistors FET1 and FET2 of the booster circuit 2 via the gate drive circuit 55.

Next, the operation of the first embodiment will be described.
Now, for example, when the vehicle is stopped and the steering wheel 6 is steered to the right by the driver, the vehicle speed Vs detected by the vehicle speed sensor 50 at this time is “0”, but is detected by the torque sensor 12. Therefore, when the steering assist control process shown in FIG. 3 is executed by the microcomputer 46 of the motor drive circuit 4, the motor phase currents Imu and Imw are read in step S1, Next, the process proceeds to step S2, the motor phase current Imv is calculated, the steering torque Ts and the vehicle speed Vs are read in step S3, and then the process proceeds to step S4, where the steering shown in FIG. 4 is performed based on the steering torque Ts and the vehicle speed Vs. Referring to assist command value calculation map to calculate the steering assist command value I _M ^*, then Nde read the motor rotation angle theta _M from the motor rotation angle detecting circuit 49 Performing three-phase Bunsho process proceeds to Luo step S6, U-phase of the in-vehicle motor 3, the target phase current value of the V-phase and W-phase Imu ^*, calculates the Imv ^* and Imw ^*, then the step S7 PID processing is performed on the deviation between the motor phase currents Imu and Imw, the motor phase current Imv calculated in step S2 and the target phase current values Imu ^* , Imv ^* and Imw ^* converted in step S6. To perform current feedback processing for calculating the current command values Iut, Ivt and Iwt, and then proceeds to step S8 to output the calculated current command values Iut, Ivt and Iwt to the gate drive circuit 45, and then proceeds to step S9. Then, it is determined whether or not to end the control, and when the control is continued, the process returns to step S1.

  When the current command values Iut, Ivt, and Iwt are output to the gate drive circuit 45 in this way, the gate drive circuit 45 performs a pulse width modulation process to obtain a duty ratio corresponding to the current command values Iut, Ivt, and Iwt. The pulse width modulation signals PWMu to PWMw and PWMu ′ to PWMw ′ are calculated, and the calculated pulse width modulation signals PWMu to PWMw are applied to the gates of the high-side field effect transistors FETu to FETw of the inverter circuit 41. ˜PWMw ′ is supplied to the gates of the low-side field effect transistors FETu ′ to FETw ′ of the inverter circuit 41, respectively, so that a three-phase drive signal is output from the inverter circuit 41 to the vehicle-mounted motor 3. Is rotated and steered according to the steering torque Ts. Generates assisted by the steering assist force is transmitted to the steering shaft 7 via a reduction mechanism 8, it is possible to steer the steering wheel 6 with a light steering force.

  At this time, the pulse width modulation signals PWMu, PWMu ′, PWMv, PWMv ′ and PWMw, PWMw ′ output from the gate drive circuit 45 are set to the high level of the inverter circuit 41 as shown in FIGS. On the side, PWMu has the longest ON interval in 1 PWM cycle, and the duty ratio increases, and then the duty ratio decreases in the order of PWMw and PWMv. 'Is the longest and the duty ratio becomes large, and then the duty ratio becomes small in the order of PWMw' and PWMu '.

  Therefore, since the gate signals PG1 and PG2 formed by the boost control circuit 5 shown in FIG. 6 are supplied to the AND gate 51 from the high side PWMu to PWMw, the output of the AND gate 51 is input. PWMu to PWMw are both turned on, and are turned on between time points t1 to t2 and t5 to t6 when the inverter circuit 41 is in a reflux state as shown in FIG. On the other hand, since the PWMu ′ to PWMw ′ on the low side are supplied to the AND gate 52, the outputs of the AND gate 52 are turned on as shown in FIG. The inverter circuit 41 is turned on between the time points t3 to t4 and t7 to t8 when the inverter circuit 41 is in the reflux state.

  Therefore, the gate pulse PG2 output from the OR gate 53 is turned on between time points t1 to t2, t3 to t4, t5 to t6, and t7 to t8 as shown in FIG. It becomes a state. Further, as shown in FIG. 5G, the gate pulse PG1 output from the inverter 54 is turned on between time points t0 to t1, t2 to t3, t4 to t5, and t6 to t7, and is turned off in other sections. It becomes.

  Therefore, in the booster circuit 2, as shown in FIG. 8, the gate pulse PG1 is in the on state and the gate pulse PG2 is in the off state immediately after the time point t0 in FIG. Therefore, the field effect transistor FET1 as the first switching element of the booster circuit 2 is turned on, the field effect transistor FET2 as the second switching element is turned off, and the booster circuit 2 is configured as shown in FIG. As shown, the negative electrode side of the charging / discharging capacitor C2 is connected to the other end side of the reactor L1 via the field effect transistor FET1. Therefore, assuming that the charging / discharging capacitor C2 is charged to 10V, the battery voltage Vb of 10V is supplied from the battery 1 to the charging / discharging capacitor C2 via the reactor L1 and the field effect transistor FET1. Then, the charging voltage (10 V) of the charging / discharging capacitor C2 is added to the battery voltage Vb to obtain a total boosted voltage of 20 V, which is supplied to the inverter circuit 41 of the motor drive circuit 4, so that the inverter circuit 41 The vehicle-mounted motor 3 can be driven at a high voltage, and the vehicle-mounted motor 3 can generate a sufficient steering assist force with a margin.

  When the time point t1 ′ immediately before the time point t1 is maintained while maintaining this boosted state, a dead time period for suppressing a through current when the PWMv is turned on at the time point t1 is reached, and the PWMv ′ is turned off first. For this reason, the inverter circuit 41 is in a semi-reflux state, and then at the time t1, the inverter circuit 41 is in a complete recirculation state. For this reason, in the inverter circuit 41, the flowing power supply current becomes “0”, and at this time t1, switching is performed in which the gate pulse GP1 is switched from the on state to the off state. At this time, in the booster circuit 2, as shown in FIG. 8B, the charge voltage of the charging / discharging capacitor C2 is discharged, for example, by 1V in the boosted state and drops to 9V, and the field effect transistor as the first switching element When the FET 1 is turned off, the drain-source voltage is 9 V, but the drain current is 0 A, and the current flowing from the reactor L1 is only the current that charges the smoothing capacitor C1.

For this reason, even if the field effect transistor FET1 as the first switching element is switched from the on state to the off state, the drain current of the field effect transistor FET1 is 0 A, so that the product of the drain current and the drain-source voltage is obtained. The switching loss expressed by is substantially zero and becomes very small.
At this time t1, the gate pulse GP2 changes from the OFF state to the ON state, so that the booster circuit 2 causes the field effect transistor FET2 as the second switching element to be in the ON state as shown in FIG. Thus, the negative electrode side of the charging / discharging capacitor C2 is connected to the negative electrode line 21n, and charging of the charging / discharging capacitor C2 is started by the current generated by the energy of the reactor L1 shown in the broken line. At this time, since the drain-source voltage of the field effect transistor FET2 is 1 V, which is a small voltage, even if a charging current flows, switching loss due to switching of the field effect transistor FET2 is suppressed to be small.

  Thereafter, the charging state of the charging / discharging capacitor C2 is continued, and when the time point t2 is reached, the gate pulse GP2 is reversed from the on state to the off state, and accordingly, the field effect as the second switching element of the booster circuit 2 The transistor FET2 switches to the OFF state as shown in FIG. 8D. In this state, the charging of the charging / discharging capacitor C2 is completed, and the negative electrode side is at 0 V of the ground potential. Since the drain-source voltage of the transistor FET2 is also 0V, the switching loss can be suppressed to a small value.

  At this time t2, the gate pulse GP1 is inverted from the off state to the on state, whereby the field effect transistor FET1 as the first switching element is turned on as shown in FIG. 8E, and the charge / discharge capacitor C2 Is connected to the reactor L1 through the field effect transistor FET1, but the inverter circuit 41 shifts from the reflux state to the semi-reflux state. However, since the current is not yet supplied to the vehicle-mounted motor 3, the reactor L1 Only the charging current for charging the smoothing capacitor C1 flows. Even when the field effect transistor FET1 is switched, the drain current is substantially zero, so that the switching loss can be suppressed to a small value.

After that, when a slight dead time elapses from the time point t2 and the PWMv ′ is turned on, when the half-reflux state is canceled and the motor energized state is restored, the boosted state similar to that in FIG. Return.
Thereafter, even when reflux occurs on the low side of the inverter circuit 41 between the time points t3 and t4, the field effect transistors FET1 and FET2 of the booster circuit 2 are switched in the same manner as described above to charge the charge / discharge capacitor C2. Thereafter, the same operation is performed every time a return state in the inverter circuit 41 occurs.

Thus, according to the above embodiment, the switching of the field effect transistors FET1 and FET2 of the booster circuit 2 is performed in a state where the inverter circuit 41 is in a reflux state and no current is supplied to the vehicle-mounted motor 3. Switching can be performed in a state where the drain-source voltage or the drain current is extremely small, and the switching loss can be suppressed to a small value. For this reason, the boosted voltage can be supplied to the inverter circuit 41 by effectively using the battery power of the battery 1, and the optimum steering assist force even when a large amount of power is required for the vehicle-mounted motor in the case of sudden steering. Can be generated, and good steering control can be performed.
Furthermore, the boost control circuit 5 can be easily configured with a combination of simple logic circuits.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, instead of the case where the booster circuit 2 constantly boosts the voltage, the booster circuit 2 boosts the voltage only when the on-vehicle motor 3 requires a high voltage.
That is, in the second embodiment, as shown in FIG. 9, the steering angle sensor 60 for detecting the steering angle is provided on the steering shaft 7 described above, and the detected steering angle value θ detected by the steering angle sensor 60 is a microcomputer. 61, the microcomputer 61 executes the boost control process, and supplies the gate pulses PG1 and PG2 output from the boost control circuit 5 to one input side of the selection switches SW1 and SW2. Gate pulses PG1s and PG2s output from the microcomputer 61 are supplied to the other input side of SW1 and SW2, and the selection switches SW1 and SW2 are switched by a selection signal SL output from the microcomputer 61. The selection switches SW1 and SW2 Each of the selected outputs of the gate drive circuit 55 Is configured to to supplied to the gate of the field effect transistors FET1 and FET2 of the booster circuit 2.

  As shown in FIG. 10, the boost control processing executed by the microcomputer 61 first reads the steering angle detection value θ detected by the steering angle sensor 60 in step S11, and then moves to step S12 and reads it. The steering angle detection value θ is differentiated to calculate the steering angular velocity θv, and then the process proceeds to step S13 to determine whether or not the calculated steering angular velocity θv is equal to or larger than a preset set value θvs, and θv <θvs. In some cases, it is determined that the steering speed of the steering wheel 6 is slow and the on-vehicle motor 3 does not require a large amount of power, and the process proceeds to step S14.

  In step S14, a low-level gate pulse PG1s is output to the selection switch SW1, and a high-level gate pulse PG2s is output to the selection switch SW2. Then, the process proceeds to step S15 to select the selection switch SW1 and For example, a selection signal SL having a logical value “0” for selecting the gate pulses PG1s and PG2s is output to SW2, and the process returns to step S11.

  On the other hand, if the determination result in step S13 is θv ≧ θvs, it is determined that the steering speed of the steering wheel 6 is fast and a large amount of electric power is required by the in-vehicle motor 3, and the process proceeds to step S16, where the selection switch After outputting the selection signal SL of the logical value “1” for selecting the gate pulses PG1 and PG2 from the boost control circuit 5 to SW1 and SW2, the process returns to step S1.

In the processing of FIG. 10, the processing of steps S11 to S13 and the steering angle sensor 60 correspond to the low output detection means.
In the second embodiment, when the steering speed of the steering wheel 6 is low, it is determined that the steering operation is normal, and the low level gate pulse PG1s and the high level of the selection switches SW1 and SW2 are determined. After the gate pulse PG2s is output, the selection signal SL is set to a logical value “0”, so that the selection switches SW1 and SW2 select the gate pulses PG1s and PG2s and output them to the field effect transistors FET1 and FET2 of the booster circuit 2. .

  For this reason, the field effect transistor FET1 of the booster circuit 2 is controlled to be always off, and the field effect transistor FET2 is always controlled to be on. For this reason, the charging / discharging capacitor C2 is always connected between the positive electrode line 21p and the negative electrode line 21n, and only the smoothing function is exhibited like the smoothing capacitor C1 while maintaining the charged state of the battery voltage Vb. The battery voltage Vb output from the reactor L1 is supplied to the inverter circuit 41 as it is because the charge / discharge control and the boosting function for adding the charging voltage to the output voltage of the reactor L1 are not provided. The vehicle-mounted motor 3 is rotationally driven by the battery voltage Vb to perform steering assist control.

If the steering wheel 6 is traveling at a low steering speed and sudden steering is performed to avoid an obstacle ahead, the steering angular speed θv calculated in step S12 in FIG. Therefore, since it becomes equal to or larger than the set value θvs, the process proceeds from step S13 to step S16, and the selection signal SL having the logical value “1” is output to the selection switches SW1 and SW2.
Therefore, the selection switches SW1 and SW2 select the gate pulses PG1 and PG2 output from the boost control circuit 5, and supply them to the field effect transistors FET1 and FET2 of the boost circuit 2 through the gate drive circuit 55, respectively. .

  For this reason, the same boosting process and charging process as in FIG. 8 in the first embodiment described above are executed. At this time, the charging / discharging capacitor C2 is already in the charged state of the battery voltage Vb. The boosted voltage can be supplied to the inverter circuit 41, and the boosted voltage is mounted on the vehicle via the inverter circuit 41 with high responsiveness even when the vehicle-mounted motor 3 such as emergency avoidance steering requires a large amount of power. The motor 3 can be supplied.

  In the second embodiment, the field effect transistors FET1 and FET2 of the booster circuit 2 are switched only when sudden steering is performed and a large amount of power is required by the vehicle-mounted motor 3, and the charge / discharge capacitor C2 In particular, the number of times of charging / discharging of the capacitor for charging / discharging can be reduced, the deterioration of charging / discharging characteristics can be reduced and the life can be extended, and the reliability of the entire apparatus can be improved. .

In the second embodiment, the case where the low output of the vehicle-mounted motor 3 is detected by the steering speed of the steering wheel has been described. However, the present invention is not limited to this, and is the change rate of the steering torque small? It may be determined whether or not the vehicle is in a low output state, and further, the vehicle-mounted motor 3 is based on the amount of change in the steering assist command value I _M ^* calculated in the steering assist control process. It may be determined whether or not is in a low output state.

In the first and second embodiments, the boost chopper constituting the booster circuit 2 is described as being configured by the reactor L1, the diode D1, and the two field effect transistors FET1 and FET2. However, the present invention is not limited to this. A field effect transistor may be applied instead of the diode D1.
Further, in the first and second embodiments, the case where the excitation windings Lu, Lv, and Lw of the in-vehicle motor 3 are Δ-connected has been described. However, the present invention is not limited to this, and the excitation winding is not limited thereto. The present invention can also be applied to the case where the lines Lu, Lv, and Lw are Y-connected.

Next, a third embodiment of the present invention will be described with reference to FIGS.
In the third embodiment, two sets of boosting units are formed in parallel in the boosting circuit 2, and the boosting control is performed by operating these boosting units alternately.
That is, in the third embodiment, as shown in FIG. 11, a charge control field effect transistor FET3 is provided in place of the diode D1 of the first embodiment, and the field effect transistor FET3 and the charge / discharge capacitor C2 are provided. A discharge control field effect transistor FET4 is provided between the connection point between the first and second output terminals to form one booster 25A, and a booster 25B having the same configuration is connected in parallel to the booster 25A. The booster circuit 2 is configured, and the booster control circuit 5 has the same configuration as that of the first embodiment except that the booster control circuit 5 is configured as shown in FIG. Reference numerals are assigned and detailed description thereof is omitted. In addition, although the Y connection motor is described as the vehicle-mounted motor 3, a Δ connection motor may be applied.

  Here, as shown in FIG. 12, the boost control circuit 5 includes a NAND gate 71 to which pulse width modulation signals PWMu ′, PWMv ′, and PWMw ′ for the low side of the inverter circuit 41 output from the gate drive circuit 45 are input. A toggle signal ST representing 1/2 of the pulse width modulation period output from the gate drive circuit 45 is input to the clock input terminal CK, and an output pulse output from the positive output terminal Q is inverted by the inverter 72 at the D input terminal. Input D-type flip-flop circuit 73, AND gate 74 to which toggle frequency dividing signal STa output from the positive output terminal of D-type flip-flop circuit 73 and output signal SA of NAND gate 71 are input, and inverter Toggle frequency division signal STb obtained by inverting the toggle frequency division signal STa output from 72 AND gate 75 to which output SA of NAND gate 71 is input, inverter 76 to which step-up permission signal SP corresponding to selection signal SL in the second embodiment described above is input, the output of inverter 76 and inverter 72 OR gate 77 to which the output STb is input, an AND gate 79 to which the output of the step-up permission signal SP and the AND gate 74 is input, and an AND gate 80 to which the output of the step-up permission signal SP and the AND gate 75 are input. It consists of and.

  The gate pulse PG11 output from the OR gate 77 is supplied to the gates of the field effect transistors FET2 and FET3 of the booster 25A, and the gate pulse PG12 output from the AND gate 79 is applied to the gate of the field effect transistor FET1 of the booster 25A. The toggle frequency division signal STa supplied from the positive output terminal Q of the D-type flip-flop circuit 73 is supplied to the gate of the field effect transistor FET4 of the booster 25A.

  The gate pulse GP21 output from the OR gate 78 is supplied to the gates of the field effect transistors FET2 and FET3 of the booster 25B, and the gate pulse PG22 output from the AND gate 80 is applied to the gate of the field effect transistor FET1 of the booster 25B. The toggle frequency division signal STb supplied and output from the inverter 72 is output to the gate of the field effect transistor FET4 of the booster 25B.

Next, the operation of the third embodiment will be described.
Now, in the steering assist control process executed by the microcomputer 46 when the steering wheel 6 is steered, for example, pulse width modulation signals PWMu to PWMw and PWMu ′ to PWMw ′ shown in FIG. 13 corresponding to the detected steering torque value Ts are obtained. It is assumed that the signal is output to the gate drive circuit 45.
At this time, it is assumed that the steering speed of the steering wheel 6 is slow, and the step-up permission signal SP having the logical value “0” is output from the microcomputer 61 in the second embodiment.

  For this reason, the gate pulses PG12 and PG22 output from the AND gates 79 and 80 are in an off state, whereby the field effect transistor FET1 as the first switching element of the boosting units 25A and 25B is in an off state, Since the gate pulses PG11 and PG21 output from the OR gates 77 and 78 are turned on, the field effect transistor FET2 and the field effect transistor FET3 as the second switching elements of the boosters 25A and 25B are turned on. For this reason, the negative electrode side of the charge / discharge capacitor C2 of the boosters 25A and 25B is connected to the negative electrode line 21n.

  Further, when the toggle signal ST is turned on at time t1 in FIG. 13 and thereby the toggle divided signal STa output from the positive output terminal Q of the D-type flip-flop circuit 73 is turned on, this is the electric field of the booster 25A. Since it is supplied to the effect transistor FET4, when the field effect transistor FET4 is turned on, the battery voltage Vb output from the reactor L1 is supplied as it is to the inverter circuit 41 via the booster 25A, and this battery voltage Vb Thus, the vehicle-mounted motor 3 is driven and controlled so as to generate a steering assist force corresponding to the steering torque detection value Ts.

  After that, when the toggle signal ST is turned off at time t2, and when the toggle signal ST is turned on again at time t3, the toggle frequency dividing signal STa output from the D-type flip-flop circuit 73 is turned off. Since the toggle frequency dividing signal STb output from the inverter 72 is turned on and supplied to the gate of the field effect transistor FET4 of the boosting unit 25B, the field effect transistor FET4 is turned on to output from the reactor L1. The applied shatter voltage Vb is supplied as it is to the inverter circuit 41 via the booster 25B, and the vehicle-mounted motor 3 is driven and controlled by this battery voltage Vb so as to generate a steering assist force according to the steering torque detection value Ts. The

In this way, in the low output state where the rotational speed of the in-vehicle motor 3 is low, the step-up permission signal SP becomes the logical value “0”, and the boosting units 25A and 25B simply perform the charging / discharging capacitor without performing the boosting action. C2 is charged to the battery voltage Vb and only smoothing is performed.
If it is necessary to steer the steering wheel 6 at a high speed and drive the vehicle-mounted motor 3 in a high output state in order to perform emergency avoidance on obstacles ahead from this state, the microcomputer 61 outputs a step-up permission signal SP having a logical value of “1”, which is input to the boost control circuit 5, so that the AND gates 79 and 80 are opened and the gate pulses output from the OR gates 77 and 78. PG11 and PG21 correspond to the toggle frequency division signals STa and STb.

  For this reason, as shown in FIG. 13, at the time t1 when the inverter circuit 41 is in the reflux state, the toggle frequency division signal STa is turned on, and this is supplied as the gate pulse PG13 to the gate of the field effect transistor FET4 of the booster 25A. Therefore, the field effect transistor FET4 is turned on, and the gate pulse PG12 is turned on at a time t1 ′ at which the inverter circuit 41 is maintained in the reflux state, which is slightly delayed. Since the field effect transistor FET1 as the first switching element is turned on, as shown in FIG. 8A in the first embodiment described above, the battery voltage Vb output from the reactor L1 is added to the battery voltage Vb. Invert the 20V boost voltage by adding the charge voltage of the charge / discharge capacitor C2. It will be immediately supplied to the circuit 41.

For this reason, since the inverter circuit 41 rotationally controls the in-vehicle motor 3 so as to generate a steering assist force based on the detected steering torque value Ts with the boost voltage, sudden steering such as emergency avoidance can be performed in an optimum state without excess or deficiency. It can be carried out.
At this time, in the booster 25B, the gate pulse PG21 is turned on at time t1, whereby the field effect transistor FET3 and the field effect transistor FET2 as the second switching element are controlled to be turned on, thereby the booster The charging / discharging capacitor C2 of 25B is maintained in a charged state.

  Thereafter, at the time t3 when the inverter circuit 41 is in the reflux state, the toggle frequency dividing signal STa is turned off, and instead, the toggle frequency dividing signal STb is turned on, whereby the gate pulse PG13 is turned off. When the gate pulse PG23 is turned on, the field effect transistor FET4 of the boosting unit 25A is turned off and the field effect transistor FET4 of the boosting unit 25B is turned on, and the gate pulse PG22 is turned on slightly later than this. Since the field effect transistor FET1 as the first switching element of the boosting unit 25B is turned on, the charging voltage of the charging / discharging capacitor C2 of the boosting unit 25B is set to the battery voltage Vb output from the reactor L1. Addition can form a boosted voltage of 20V, which is Since supplied to inverter circuit 41, it can continue to be high-voltage-vehicle motor 3 in the inverter circuit 41. Also at this time, in the other boosting unit 25A, the field effect transistor FET3 and the field effect transistor FET2 as the second switching element are turned on, and the charge / discharge capacitor C2 of the boosting unit 25A is maintained in the charged state.

As described above, in the third embodiment, the booster circuit 2 has a configuration in which the two boosters 25A and 25B are connected in parallel, and when the boosted voltage is formed, one of the boosters 25A and 25B is boosted. Since the control state is set, the other is set to the charge state, and these are alternately switched to perform charge and discharge control alternately, it is possible to form a stable boost voltage without fluctuation of the boost voltage.
In addition, since the field effect transistors FET1 to FET4 as the switching elements of the voltage boosters 25A and 25B are all switched while the inverter circuit 41 is in the reflux state, the switching loss is reduced as in the first embodiment described above. The optimum boosted voltage can be formed by reducing the battery power and effectively using the battery power.

  Further, when the on-vehicle motor 3 does not require a large amount of power, the boosting units 25A and 25B are maintained in a charged state by using the charging / discharging capacitor C2 as a smoothing capacitor as in the second embodiment described above. When the in-vehicle motor 3 requires a large amount of power, the charging voltage of the charging / discharging capacitor C2 of any boosting unit is immediately added to the battery voltage Vb output from the reactor L1 to instantly form the boosting voltage. It is possible to shift to the boost control state with high responsiveness.

In the above embodiment, the case where the steering assist control process is executed by the microcomputer 46 of the motor drive circuit 4 has been described. However, the present invention is not limited to this, and a steering assist control device that separately performs the steering assist control is provided. A motor current command value may be supplied from the steering assist control device to the microcomputer 46 for motor drive control.
Furthermore, although the case where the motor rotation angle is detected using the resolver 13 has been described in the above embodiment, the present invention is not limited to this, and a rotation angle sensor using a rotary encoder, a Hall element, or the like is applied. You may make it do.

Furthermore, although the case where the present invention is applied to an electric power steering device has been described in the above embodiment, the present invention is not limited to this, and the present invention may be applied to an electric brake device. As this electric brake device, for example, as shown in FIG. 15, there are friction pads 62, 63 facing both surfaces of the brake disc 61, and a ball screw shaft 65 of a ball screw mechanism 64 is connected to one friction pad 63. The ball nut 66 of the ball screw mechanism 64 includes a caliper 68 connected to the in-vehicle motor 3 through a speed reduction mechanism 67 such as a planetary gear mechanism, for example, and the in-vehicle motor 3 applies a boosted voltage from the booster circuit 2 described above. The motor drive circuit 4 is driven and controlled. Here, the microcomputer 46 of the motor drive circuit 4 is used for braking based on the brake pedal depression amount, the braking amount required for yaw rate control, traction control, etc. instead of the steering assist control processing of FIG. A similar process is executed except that a brake control process for calculating a current value is executed. In addition, the present invention can be applied to any other vehicle-mounted motor control device.
Furthermore, in the above embodiment, a case where a brushless motor is applied as the in-vehicle motor 3 and this brushless motor is driven by three-phase AC driving has been described. However, the present invention is not limited to this, and AC driving of five or more phases is performed. You may make it do.

It is a schematic block diagram which shows embodiment at the time of applying this invention to an electric power steering apparatus. It is a block diagram which shows an example of the booster circuit, boost control circuit, and motor drive circuit which can apply this invention. It is a flowchart which shows an example of the steering assistance control processing procedure performed with the microcomputer of a motor drive circuit. It is a characteristic diagram which shows the control map for steering assistance electric current value calculation. It is a time chart with which it uses for description of operation | movement of 1st Embodiment. It is explanatory drawing which shows the return state of the high side of an inverter circuit. It is explanatory drawing which shows the return state of the low side of an inverter circuit. It is explanatory drawing with which it uses for description of operation | movement of the booster circuit in 1st Embodiment. It is a block diagram which shows the 2nd Embodiment of this invention. It is a flowchart which shows an example of the pressure | voltage rise control processing procedure in 2nd Embodiment. It is a block diagram which shows the 3rd Embodiment of this invention. It is a block diagram which shows the pressure | voltage rise control circuit of 3rd Embodiment. It is a time chart with which it uses for description of operation | movement of 3rd Embodiment. It is a block diagram which shows embodiment at the time of applying this invention to an electric brake device. It is a time chart with which it uses for description of the switching loss of a prior art example. It is a time chart used for more detailed explanation of switching loss.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Battery, 2 ... Boosting circuit, 3 ... Vehicle-mounted motor, 4 ... Motor drive circuit, 5 ... Boosting control circuit, 6 Steering wheel, 7 ... Steering wheel, 11 ... Steering wheel, 12 ... Steering torque sensor, 13 ... Resolver , L1 ... reactor, FET1, FET2 ... field effect transistor, D1 ... diode, C2 ... charge / discharge capacitor, 41 ... inverter circuit, 45 ... gate drive circuit, 46 ... microcomputer, 47u, 47w ... motor current detection circuit, 48 DESCRIPTION OF SYMBOLS ... Steering torque detection circuit, 49 ... Motor rotation angle detection circuit, 50 ... Vehicle speed sensor, 60 ... Steering angle sensor, 61 ... Microcomputer 61 ... Brake disk, 62, 63 ... Friction pad, 64 ... Ball screw mechanism, 67 ... Deceleration Mechanism, 68 ... caliper

Claims (5)

Boosting means for boosting a power supply voltage output from a DC power supply, motor driving means for driving and controlling a multiphase motor with a pulse width modulation signal based on the boosted voltage output from the boosting means, and return of the motor driving means A boost control means for detecting timing and performing switching control of the boost means at the detected reflux timing;
The boosting means includes a reactor having one end connected to the positive electrode side of a DC power supply, a diode connected in the forward direction to the other end of the reactor , a charge / discharge capacitor connected to the output side of the diode, A first switching element connected in parallel with the diode and the charging / discharging capacitor; and a first switching element connected between a connection point between the first switching element and the charging / discharging capacitor and a negative electrode side of the DC power supply. And an output terminal to the motor drive circuit derived from a connection point between the diode and the charging / discharging capacitor and a connection point between the second switching element and the negative electrode side of the DC power supply. With a booster,
The boost control means controls the first switching element to be in an on state and the second switching element to be in an off state when the reflux timing is not detected, and the accumulated voltage of the charge / discharge capacitor is The boosted voltage superimposed on the DC power supply voltage input through the reactor is output to the motor driving means, and when the start of the reflux timing is detected, the first switching element is turned off and the second switching element is turned off. When the switching element is turned on, the charging / discharging capacitor is charged with a power supply voltage, and when the return timing ends, the second switching element is turned off and then the first switching element is turned on. A vehicle-mounted motor control device that performs boost control for returning to a boosted voltage supply state. The boost control means has low output detection means for detecting a low output state of the multiphase motor, and the first switching element is detected when the low output detection means detects the low output state of the multiphase motor. 2. The vehicle-mounted device according to claim 1 , wherein the charging / discharging of the charging / discharging capacitor is stopped by turning off the second switching element and controlling the second switching element to an on state . Motor control device. The boost control unit is configured to detect, as a return timing, a timing at which all switching elements are turned on on either the high side or the low side based on a pulse width modulation signal of the motor driving unit. The on-vehicle motor control device according to claim 1, wherein: An electric power steering apparatus comprising the on-vehicle motor control apparatus according to any one of claims 1 to 3 . An electric brake device comprising the on-vehicle motor control device according to any one of claims 1 to 3 .

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