JP3518986B2 - Motor control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device, and more particularly to a motor control device that drives a motor based on a pulse width modulated (PWM) signal (hereinafter referred to as PWM drive).

[0002]

2. Description of the Related Art Generally, in a method of driving a motor with a bridge circuit, one of a pair of switching elements in a desired flow direction is driven by a pulse width modulated signal and the other switching element of the pair continues. ON-drive to turn off a pair of switching elements that are not in the flow direction, and a single-phase single-sided chopper method that drives a pair of switching elements in the flow direction by a pulse width modulated signal to switch a pair in the non-flow direction. A single-phase double-sided chopper system that turns off the elements, and a signal that drives a pair of switching elements in the flow direction with a pulse-width-modulated signal and inverts a pair of switching elements that are not in the flow direction from the previous pair of drive signals. Three types of two-phase double-sided chopper system driven by are known. Further, these three types of bridge circuit driving methods are switched according to the motor current target value, as disclosed in, for example, Japanese Patent Laid-Open No. 8-336293.

Next, the characteristics of each bridge circuit drive system will be described. FIG. 19 shows a vehicle-mounted battery 1, a current detection resistor 6, when a motor is driven by a single-phase one-sided chopper method,
A power running current Ia represented by a solid line passing through the flow paths of the switching element 3a, the motor 2 and the switching element 3d, and a regenerative current I indicated by a broken line passing through the flow paths of the motor 2, the switching element 3d and the flywheel diode 4c.
It shows the relationship of b. From the flow path in the figure, it can be seen that the regenerative current Ib is attenuated by the electric time constant of the motor.

FIG. 20 shows a flow path of a vehicle-mounted battery 1, a current detection resistor 6, a switching element 3a, a motor 2 and a switching element 3d when the motor is driven by a single-phase double-sided chopper method and a two-phase double-sided chopper method. The relationship between the power running current Ic represented by the solid line, the motor 2, the flywheel diode 4b, the current detection resistor 6, the vehicle-mounted battery 1, and the regenerative current Id represented by the broken line passing through the flow path of the flywheel diode 4c is shown. It can be seen from the flow path in the figure that the regenerative current Id is regenerated by the power supply and immediately attenuated. That is, the single-phase double-sided chopper method or the two-phase double-sided chopper method is characterized by better controllability of the regenerative current than the single-phase single-sided chopper method. On the other hand, since the switching loss increases as the number of switching elements increases, heat generation increases in the order of the two-phase double-sided chopper, the single-phase double-sided chopper, and the single-phase single-sided chopper.

In the above motor control device, when control is performed such that the motor is abruptly reversed using the single-phase one-sided chopper system, the directions of the counter electromotive voltage and the applied voltage of the motor coincide with each other, as shown in FIG. As described above, the motor current has an overshoot. The back electromotive force of the motor is proportional to the rotation speed of the motor, and it is the applied voltage from when the energization direction to the motor is reversed until the rotation direction is reversed with a delay due to the moment of inertia of the motor. And the back electromotive force becomes the same direction. Therefore, when reversing the rotation direction of the motor, an excessive voltage is applied to the motor, causing an overshoot in the motor current. In order to solve this problem, in the conventional device, for example, Japanese Patent Application Laid-Open No. 3-99979.
As disclosed in the publication, when it is determined that an overcurrent is flowing through the motor, the drive system is switched to a drive system having good controllability of the regenerative current to suppress the overcurrent of the motor current (see FIG. 22).

[0006]

However, when the motor current is feedback controlled, the overcurrent is originally suppressed by the feedback action. Therefore, in the above-mentioned conventional device, the bridge circuit drive method is not switched and the overcurrent does not flow in the motor, but the motor current becomes oscillatory due to overshoot in the motor current or hunting of the current control, resulting in fluctuation of torque. There was a problem that it produced a strange noise. Further, when the motor current target value is small, the motor current may not exceed the overcurrent determination threshold value, and there is a problem that the overshoot that does not result in the overcurrent cannot be prevented.

The present invention has been made in order to solve the above-mentioned problems, and prevents the overcurrent of the motor current in advance and surely suppresses the overshoot and hunting of the motor current. An object of the present invention is to obtain a motor control device capable of Another object of the present invention is to obtain a motor control device that can obtain the above-mentioned prevention and suppression effects even when the motor current is feedback-controlled.

[0008]

According to another aspect of the present invention, there is provided a motor control device for detecting a current of a motor connected to a bridge circuit as a load, a motor current detection value and a motor current target value. Current feedback control is performed to calculate a duty ratio for driving the switching element of the bridge circuit, and a switching element drive unit for driving the switching element is provided, and the switching element drive duty ratio is equal to or less than a first predetermined value. For example, the drive system for driving the switching element is a bridge circuit drive system for regenerating a motor current to a power supply.

A motor control device according to a second aspect of the invention is
In the invention of claim 1, the bridge circuit drive system is composed of a plurality of drive systems having different regenerative current controllability, and when the motor current is controlled, the switching element drive duty ratio is equal to or less than a first predetermined value. In this case, the drive system having a better controllability of the regenerative current is switched to.

A motor control device according to a third aspect of the invention is
In the invention of claim 2, a single-phase single-sided chopper system and a single-phase double-sided chopper system are used as the plurality of drive systems.

A motor control device according to a fourth aspect of the invention is
In the invention of claim 2, a single-phase single-sided chopper system and a two-phase double-sided chopper system are used as the plurality of drive systems.

A motor control device according to a fifth aspect of the invention is
In the invention of claim 3 or 4, in the single-phase one-sided chopper method, the bridge circuit is composed of four sets of switching elements, and one of the pair of switching elements in the flow direction is driven by a pulse width modulated signal, This is a drive system in which the other switching element of the pair is continuously turned on and the pair of switching elements not in the flow direction are turned off.

A motor control device according to a sixth aspect of the present invention is
In the invention of claim 3, in the single-phase double-sided chopper method, the bridge circuit is composed of four sets of switching elements, and a pair of switching elements in the flow direction are driven by a pulse-width-modulated drive signal. This is a driving method for turning off a pair of switching elements other than the above.

A motor control device according to a seventh aspect of the invention is
In the invention of claim 4, in the two-phase double-sided chopper method, the bridge circuit is composed of four sets of switching elements, and a pair of switching elements in the flow direction are driven by a pulse-width-modulated drive signal. This is a drive system in which a pair of switching elements other than the above are driven by a signal obtained by inverting the drive signal.

According to another aspect of the motor control device of the present invention,
In the invention according to any one of claims 1 to 7, if the degree of change in the motor current is equal to or greater than a second predetermined value, the bridge circuit driving method is switched.

A motor control device according to a ninth aspect of the invention is
In the invention according to any one of claims 1 to 7, if the degree of change of the switching element drive duty ratio is not less than a third predetermined value, the bridge circuit drive method is switched.

According to a tenth aspect of the present invention, in the motor control device according to any one of the first to seventh aspects of the invention, if the degree of change in the deviation of the motor current is not less than a third predetermined value, the bridge circuit drive system is used. To switch.

According to an eleventh aspect of the present invention, in the motor control device according to any one of the first to tenth aspects of the invention, when the bridge circuit drive system switching condition continues for a predetermined time,
The bridge circuit driving method is switched.

According to a twelfth aspect of the present invention, in the motor control device according to any one of the first to eleventh aspects of the present invention, the bridge circuit drive system is switched only for a predetermined time after the bridge circuit drive system switching condition is satisfied.

According to a thirteenth aspect of the present invention, in the motor control apparatus according to any one of the first to eleventh aspects of the present invention, after the switching of the bridge circuit driving method, until the switching element driving duty ratio becomes a fourth predetermined value or more. The motor control in the drive system is continued.

According to a fourteenth aspect of the present invention, in the motor control device according to the first or second aspect of the present invention, the bridge circuit driving method is a three-phase bridge circuit driving method.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. Embodiment 1. FIG. 1 is a configuration diagram showing an example of a case in which a motor control device for controlling a motor is applied to a power steering of a vehicle by switching a bridge circuit drive system to a single-phase double-sided chopper system or a single-phase single-sided chopper system.
In FIG. 1, 1 is an in-vehicle battery as a DC power source, 2
Is a motor connected to the bridge circuit as a load, 3a-
3d is a switching element, 4a to 4d are flywheel diodes connected in antiparallel to the switching elements 3a to 3d, and 5 is a bridge circuit composed of the switching elements 3a to 3d.

Reference numeral 8 denotes a motor current detecting means for detecting a motor current, which is composed of a current detecting resistor 6 and an amplifier 7 connected between the DC power source 1 and the bridge circuit 5. Reference numeral 9 is a switching element drive circuit for driving the switching elements 3a to 3d, which is composed of switching element drivers 10a to 10d. Reference numeral 11 is a drive system switching means, which is a drive system switching signal Sig.
1, Sig2 switches the driving method of the switching elements 3a to 3d of the bridge circuit 5, and is composed of OR gates 12a and 12b.

Reference numeral 13 is a control means, which is a PWM signal PWM1, PW for driving the switching elements 3a to 3d.
PWM modulator 14 for outputting M2, input / output port 15a for outputting drive system switching signals Sig1, Sig2, input / output port 15b for inputting a vehicle speed signal detected by vehicle speed detecting means 21, motor current An A / D converter 16a for analog / digital converting the motor current detection value detected by the detecting means 8 and an A / D converter 16b for A / D converting the steering torque detection value of the steering wheel detected by the torque detecting means 20. , Vehicle speed detection means 2
Based on the detected values such as the vehicle speed signal from 1, the motor current detection value from the motor current detection means 8 and the steering torque detection value from the torque detection means 20, the ROM 18 and the data holding the program are temporarily stored. It is configured by a microcomputer (CPU) 17 that performs a preset process by using a RAM 19 that is temporarily stored. The components 9, 11, and 13 form a switching element driving means.

Next, the operation of the first embodiment will be described with reference to FIG.
It will be described according to the flowchart shown in FIG. This program shall be called at regular intervals. First, in step S1, the steering torque detection value Ts, the vehicle speed Vs, and the motor current detection value Is are read. Next, in step S2, a motor current target value It calculated from the steering torque and the vehicle speed Vs, for example, as shown in FIG. 3, is calculated from the steering torque detection value Ts and the vehicle speed Vs. Next, in step S3, for example, as disclosed in Japanese Patent Laid-Open No. 8-336293,
The bridge circuit driving method is set based on the motor current target value It. Next, in step S4, if the set bridge circuit drive method is not the single-phase one-sided chopper method, the process proceeds to step S7, in which the motor current is determined based on the deviation between the motor current target value It and the motor current detection value Is. Feedback control is performed to obtain the duty ratio Dt (n).

Next, in step S9, the bridge circuit 5 is driven by the single-phase double-sided chopper in steps S11 to S13 according to the energization polarity. That is, the motor current target value It
If the flow direction is right, the process proceeds to step S11, and the output signal of the control means 13 is set as shown in FIG. 5 so as to flow right. If the motor current target value It is 0, the process proceeds to step S12, and the output signal of the control means 13 is set as shown in FIG. 6 so as to turn off all the switching elements. If the flow direction is left, the process proceeds to step S13, and the output signal of the control means 13 is set as shown in FIG. 7 so as to flow in the left direction.

FIG. 4 shows operation waveforms when the motor current overshoot is prevented in steps S4 to S6. As shown in the figure, when reversing the motor,
The direction of the back electromotive voltage and the direction of the applied voltage match, an excessive voltage is applied to the armature resistance, and the single-phase single-sided chopper system cannot control it sufficiently and the motor current overshoots. At that time, the current feedback control in step S8, which will be described later, acts and the motor drive duty ratio becomes a value close to zero.

Therefore, the driving method of the switching element is checked in step S4, and if it is a single-phase one-sided chopper method, the process proceeds to step S5. In step S5, the drive duty ratio of the motor is checked, and if the current duty ratio Dt (n) is less than or equal to the first predetermined value D1, the drive system is switched to the single-phase double-sided chopper system with good regenerative current controllability. This suppresses overshoot of the motor current, as shown in FIG. The operation after the next step S7 is exactly the same as that described above, and a description thereof will be omitted.

On the other hand, if the switching element drive duty ratio Dt (n) at present is larger than the predetermined value D1, the process proceeds from step S5 to step S8, and the switching element drive duty ratio Dt (n) is calculated in the same manner as step S7. To do. Next, in step S10, the bridge circuit 5 is driven by the single-phase one-side chopper in steps S14 to S16 according to the energization polarity. That is, the motor current target value It
If the flow direction is right, the process proceeds to step S14, and the output signal of the control means 13 is set as shown in FIG. 8 so as to flow right. If the motor current target value It is 0, the output signal of the control means 13 is set as shown in FIG. 6 so as to proceed to step S15 and turn off all the switching elements. If the flow direction is left, the process proceeds to step S16, and the output signal of the control means 13 is set as shown in FIG. 9 so as to flow in the left direction.

As described above, according to the present embodiment, the bridge circuit drive method is forcibly used in accordance with the switching element drive duty ratio that changes due to the action of the motor current feedback control, and the single-phase piece with poor controllability of the regenerative current is obtained. By switching from the side chopper method to the single-phase double-sided chopper method which has good regenerative current controllability, it is possible to suppress overshoot and hunting of the motor current.

Embodiment 2. Although the first embodiment has been described for switching the bridge circuit driving method from the single-phase one-sided chopper method to the single-phase both-sided chopper method, in the present embodiment, when the bridge circuit driving method is switched, the single-phase one-sided chopper method is changed. A method of switching to the two-phase double-sided chopper system will be described. The configuration of the control device in the present embodiment is shown in FIG. Drive system switching means 1 of FIG.
The structure is the same as that of the first structure except that the drive system switching means 11A is composed of AND gates 12c and 12d and NOT gates 12e and 12f.

FIG. 11 is a flow chart for explaining the present embodiment. Steps S11, S12, S13 for driving the switching elements by the single-phase double-sided chopper method in the flow chart of the first embodiment are driven by the two-phase double-sided chopper method. It is replaced with steps S17, S18, and S19. Here, in step S17, the output signal of the control means 13 is set as shown in FIG. 12, in step S18, the output signal of the control means 13 is set as shown in FIG. 13, and in step S19 it is shown in FIG. And the switching element is driven by the two-phase double-sided chopper method.

As described above, according to the second embodiment,
Even if the bridge circuit drive system is switched from the single-phase single-sided chopper system with poor regenerative current controllability to the two-phase double-sided chopper system with good regenerative current controllability, the same effect as in the first embodiment is achieved.

In the first and second embodiments, examples in which the single-phase double-sided chopper method and the two-phase double-sided chopper method are used as the bridge circuit driving method with good controllability of the regenerative current have been described. The same effect can be obtained with any drive system as long as it is a bridge circuit drive system that regenerates power.

In the first and second embodiments, the example in which the DC brush motor is driven by the single-phase bridge circuit is shown, but it goes without saying that the present invention can be applied to the case where the DC brushless motor is driven by the three-phase bridge circuit. .

Embodiment 3. In the present embodiment, an example in which the drive method is switched when it is determined that the motor current may overshoot if the degree of change in the motor current is equal to or greater than the second predetermined value is shown. The configuration of the motor control device in the present embodiment is exactly the same as the configuration shown in the first embodiment.

Next, the operation of this embodiment will be described with reference to FIG.
It will be described according to the flowchart shown in FIG. This program is also called at regular intervals. First, steps S1 to S3 are sequentially executed in the same manner as in the first embodiment. Next, in step S4, when it is determined that the set bridge circuit driving method is not the single-phase single-sided chopper method, the process proceeds to step S7, and the bridge circuit 5 is driven by the single-phase double-sided chopper method. Since step S7 and subsequent steps are exactly the same as those in the first embodiment, description thereof will be omitted.

On the other hand, if it is determined in step S4 that the set bridge circuit driving method is the single-phase one-sided chopper method, the process proceeds to step S20, in which the degree of change in the motor current detection value, that is, the motor current in the previous calculation is determined. Target value Is (n
-1) and the difference between the motor current target value Is (n) at the time of this calculation are checked. When the degree of change in the motor current is large, overshoot occurs in the motor current, and the settling time is likely to be long in the bridge circuit drive system in which the controllability of the regenerative current is poor. Further, when the hunting of the motor current cannot be suppressed by the method according to the above-described embodiment, it is considered that the motor current is fluctuating at a speed that is impossible under normal conditions. Therefore, when | Is (n) −Is (n−1) | is the second predetermined value I ₁ or more, the bridge circuit driving method is switched to the single-phase double-sided chopper method. Since the subsequent step S7 and subsequent steps are exactly the same as those in the first embodiment, the description thereof will be omitted.

If it is determined in step S20 that the above conditions are not satisfied, the process proceeds to step S8, and the bridge circuit 5 is driven by the single-phase one-sided chopper method. Since step S8 and subsequent steps are exactly the same as those in the first embodiment, description thereof will be omitted.

As described above, according to the third embodiment,
When the degree of change in the motor current is equal to or greater than the second predetermined value, it is determined that the motor current is likely to overshoot,
The bridge circuit drive system is switched to the single-phase double-sided chopper system with good controllability of regenerative current in advance. Thereby, overshooting or hunting of the motor current can be suppressed.

Fourth Embodiment In the present embodiment, if the degree of change in the motor drive duty ratio is equal to or greater than the third predetermined value, the deviation of the motor current is abruptly changed, and it is determined that the motor current may overshoot and the drive method is determined. An example of switching between is shown. The configuration of the device in the present embodiment is exactly the same as the configuration shown in the first embodiment.

The operation of this embodiment will be described with reference to the flowchart shown in FIG. This program also
It shall be called at regular intervals. First, steps S1 to S3 are sequentially executed in the same manner as in the first embodiment.
Next, in step S4, if the set bridge circuit driving method is not the single-phase single-sided chopper method, the process proceeds to step S7, and the bridge circuit 5 is driven by the single-phase double-sided chopper method. Since step S7 and subsequent steps are exactly the same as those in the first embodiment, the description thereof will be omitted.

On the other hand, if the set bridge circuit drive system is the single-phase one-sided chopper system in step S4, the process proceeds to step S8, and the switching element drive duty ratio Dt (n) is calculated as in step S7. Next, in step S21, the degree of change in the motor drive duty ratio is checked. As a result of performing feedback control of the motor current, when the duty ratio is rapidly decreasing, it is considered that the motor current is likely to overshoot, as in the first embodiment. Therefore, by switching to a drive system in which the controllability of the regenerative current is good when the degree of change in the drive duty ratio of the motor is large, it is possible to prevent overshooting earlier.

However, the duty ratio Dt (n) calculated in step S8 and the duty ratio Dt (n
If the absolute value of the difference of -1) is not less than the third predetermined value D2,
In step S22, the bridge circuit drive system is switched to the single-phase double-sided chopper system. In step S22, the duty ratio is changed depending on the bridge circuit driving method even when the same motor current is passed, so that the motor current does not fluctuate remarkably, for example, by the method disclosed in Japanese Patent Laid-Open No. 8-336293. I do. Since step S9 and subsequent steps are exactly the same as those in the first embodiment, the description thereof will be omitted.

On the other hand, if the above condition is not satisfied in step S21, the process proceeds to step S10, and the bridge circuit 5 is driven by the single-phase one-sided chopper method. Step S1
Since 0 and subsequent steps are exactly the same as those in the first embodiment, description thereof will be omitted.

As described above, according to the fourth embodiment,
If the degree of change in the motor drive duty ratio that changes due to the action of the motor current feedback control is larger than the third predetermined value, it is determined that the motor current is likely to overshoot, and the bridge circuit drive method is set in advance for the regenerative current. Switch to the single-phase double-sided chopper method with good controllability. This makes it possible to prevent motor current overshoot and hunting earlier.

The motor drive duty ratio obtained as a result of the current feedback control is the result of multiplying the deviation of the motor current by a predetermined gain, or the integrated value thereof. Therefore, even if the drive method is switched when the degree of change in the deviation of the motor current is equal to or greater than the third predetermined value, the same effect can be obtained.

Embodiment 5. In the above-described first to fourth embodiments, the bridge circuit drive system is switched when the bridge circuit drive system switching condition is satisfied. However, when the detection noise of the motor current detection value is large, the switching condition is not erroneously determined. In addition, the drive system may be switched when the drive system switching condition continues for a predetermined time. Note that this embodiment can be applied to any of the above-described second to fourth embodiments, but here, the case where it is applied to the first embodiment will be described.

The operation of this embodiment will be described with reference to the flowchart shown in FIG. This program also
It shall be called at regular intervals. First, steps S1 to S3 are sequentially executed in the same manner as in the first embodiment. Next, if the bridge circuit driving method set in step S3 is not the single-phase one-sided chopper method, the process proceeds from step S4 to step S7. Since step S7 and subsequent steps are exactly the same as those in the first embodiment, description thereof will be omitted.

On the other hand, if the bridge circuit driving method set in step S3 is the single-phase one-sided chopper method, the process proceeds from step S4 to step S5, and steps S5, S23,
In S24, S25, and S30, the time when the motor drive duty ratio becomes equal to or less than the first predetermined value is measured, and the bridge circuit drive system is switched. In step S5, if the current duty ratio Dt (n) is equal to or larger than the predetermined value D1, step S5
The timer I is cleared at 30 and the process proceeds to step S8. Since step S8 and subsequent steps are exactly the same as those in the first embodiment, description thereof will be omitted.

On the other hand, if the duty ratio at the present time is smaller than the predetermined value D1 in step S5, in step S23,
Count up timer I. Next, step S24.
Then, if the timer I is equal to or less than the predetermined value T1, the process proceeds to step S8. Since step S8 and subsequent steps are exactly the same as those in the first embodiment, description thereof will be omitted. On the other hand, in step S24,
If the timer I is larger than the predetermined value T1, step S25
Then, assign T1 to timer I and clip,
In order to switch the bridge circuit driving method to the single-phase double-sided chopper method, the process proceeds to step S7. After step S7,
Since it is exactly the same as the case of the first embodiment, its explanation is omitted.

As described above, according to the fifth embodiment,
When the bridge circuit drive system switching condition continues for a predetermined time, the bridge circuit drive system is switched to a drive system with a good regenerative current, so it is possible to prevent erroneous determination of drive system switching due to the influence of noise in the motor current detection value. it can.

Sixth Embodiment In the first to fifth embodiments described above, after the bridge circuit drive system switching condition is satisfied, the bridge circuit drive system may be switched only for a predetermined time with good controllability of the regenerative current. The present embodiment can be applied to any of the above-described second to fifth embodiments, but here, the case where it is applied to the first embodiment will be described.

The operation of this embodiment will be described with reference to the flowchart shown in FIG. This program also
It shall be called at regular intervals. First, steps S1 to S3 are sequentially executed in the same manner as in the first embodiment. Next, steps S4, S26, S27 and S28.
Then, the time after the motor drive duty ratio Dt becomes equal to or less than the predetermined value D1 is measured. First, in step S4, if the bridge circuit drive method is not the single-phase one-sided chopper method,
In step S28, the timer II is counted up. On the other hand, if the bridge circuit driving method is the single-phase one-side chopper method, the process proceeds to step S26, and the switching element driving duty ratio at the present time is checked for Dt (n). Dt
If (n) is less than or equal to the predetermined value D1, the timer II is cleared in step S27. If Dt (n) is larger than D1, the process proceeds to step S28 and the timer II is counted up.

In step 29, the drive system of the motor is determined based on the timer II measured as described above. That is, if the timer II is equal to or less than the predetermined value T2 in step S29, the process proceeds to step S7, and the motor 2 is driven by the single-phase double-sided chopper method regardless of the driving method determined in step S3. If the timer II is larger than the predetermined value T2, T2 is substituted into the timer II in step S31 to be clipped, and the process proceeds to step S32, and to step S7 or step S8 depending on the driving method determined in step S3. Hereinafter, as in the other embodiments, the motor 2 using the single-phase double-sided chopper method or the single-phase single-sided chopper method is used.
To drive. The timer II is initialized to T2 when the CPU 17 is power-on reset, and the first time follows the drive method determined in step S3.

As described above, according to the sixth embodiment,
By switching to the bridge circuit drive method in which the controllability of the regenerative current is good only for a predetermined time after the bridge circuit drive method switching condition is satisfied, the motor controllability and the heat generation of the switching element are improved as compared with the motor control devices of the first to fifth embodiments. The motor current overshoot can be suppressed with almost no influence on the motor current. In addition, it is possible to prevent the controllability of the current from deteriorating due to hunting of the switching of the driving method.

Embodiment 7. In the sixth embodiment described above, the duration when the drive system with good controllability of the regenerative current is set regardless of the drive system in step S3 is limited to the predetermined time T2 or less, but the motor drive duty ratio is It may be continued until it becomes the predetermined value D3 of 4 or more. Although heat generation can be suppressed in the sixth embodiment,
When the direction of the motor back electromotive force and the direction of the motor applied voltage match and the motor current is likely to overshoot for a long period of time, the controllability of the regenerative current may periodically be poor and the bridge circuit drive system may be restored. There is. In the present embodiment, such a problem can be prevented.

Further, in the above-described first and second embodiments, when the motor drive duty ratio becomes equal to or greater than the predetermined value D1, the bridge circuit drive system returns to the single-phase one-side chopper system, so that the drive system may be switched. There is. In the present embodiment, such a problem can be avoided by setting D3> D1 and providing the switching determination threshold with hysteresis. Of course, also in the switching method based on the degree of change shown in the third and fourth embodiments, the switching of the bridge circuit driving method may be continued until the degree of change becomes the fourth predetermined value or less. The first embodiment shown above
It is needless to say that the performance can be further improved by simultaneously performing any one or more of the items 1 to 7.

[0059]

According to the invention of claim 1, the motor current detection means for detecting the current of the motor connected to the bridge circuit as a load, and the current feedback control from the motor current detection value and the motor current target value are performed. A driving method for driving a switching element of a bridge circuit, comprising a switching element driving means for calculating a duty ratio for driving the switching element, and driving the switching element, if the switching element driving duty ratio is not more than a first predetermined value Is a bridge circuit drive system that regenerates the motor current to the power supply, so that overcurrent of the motor current can be prevented in advance and motor current overshoot and hunting can be suppressed. In some cases, the steering feeling can be improved. is there.

According to the second aspect of the present invention, the bridge circuit drive system is composed of a plurality of drive systems having different regenerative current controllability, and the switching element drive duty ratio is the first when the motor current is controlled. If it is less than a predetermined value, the drive method with better controllability of regenerative current is switched.
There is an effect that it is possible to suppress overshoot and hunting of the motor current.

According to the third aspect of the present invention, since the single-phase single-sided chopper system and the single-phase double-sided chopper system are used as the plurality of drive systems, the drive system having better controllability of the regenerative current, that is, the single-phase double-sided chopper system is adopted. It is possible to switch over, and thus it is possible to suppress overshoot and hunting of the motor current.

According to the fourth aspect of the present invention, the single-phase single-sided chopper method and the two-phase double-sided chopper method are used as the plurality of drive methods. It is possible to switch over, and thus it is possible to suppress overshoot and hunting of the motor current.

According to the fifth aspect of the invention, in the single-phase one-sided chopper system, the bridge circuit is composed of four sets of switching elements, and one of the pair of switching elements in the flow direction is driven by the pulse width modulated signal. However, since the drive method is such that the other switching element of the pair is continuously turned on and the pair of switching elements that are not in the flow direction are turned off, the heat generated by the switching element can be suppressed to a low level.

According to the sixth aspect of the invention, in the single-phase double-sided chopper system, the bridge circuit is composed of four sets of switching elements, and a pair of switching elements in the flow direction are driven by a pulse width modulated drive signal. Since it is a drive system that turns off a pair of switching elements that are not in the flow direction,
This has the effect of obtaining good regenerative current controllability.

According to the seventh aspect of the invention, in the two-phase double-sided chopper system, the bridge circuit is composed of four sets of switching elements, and a pair of switching elements in the flow direction are driven by a pulse width modulated drive signal. Since it is a drive system in which a pair of switching elements that are not in the flow direction are driven by a signal obtained by inverting the drive signal, there is an effect that good controllability of the regenerative current is obtained.

According to the eighth aspect of the present invention, if the degree of change of the motor current is not less than the second predetermined value, the bridge circuit driving method is switched. Therefore, the bridge circuit driving method is changed from the single-phase one-sided chopper method to the regenerative current. It is possible to switch to the single-phase double-sided chopper method or the two-phase double-sided chopper method, which has good controllability, and thus it is possible to suppress overshoot and hunting of the motor current.

According to the ninth aspect of the invention, if the change rate of the switching element drive duty ratio is equal to or greater than the third predetermined value, the bridge circuit drive system is switched. Therefore, the bridge circuit drive system is changed from the single-phase one-side chopper system to It is possible to switch to the single-phase double-sided chopper method or the two-phase double-sided chopper method, which has good controllability of the regenerative current, and thus it is possible to suppress overshoot and hunting of the motor current.

According to the tenth aspect of the present invention, when the degree of change in the deviation of the motor current is not less than the third predetermined value, the bridge circuit driving method is switched. Therefore, the bridge circuit driving method is changed from the single-phase one-side chopper method to the regenerative method. It is possible to switch to the single-phase double-sided chopper system or the two-phase double-sided chopper system with good current controllability, and thus there is an effect that the motor current overshoot and hunting can be suppressed.

According to the eleventh aspect of the present invention, since the bridge circuit drive system is switched when the bridge circuit drive system switching condition continues for a predetermined time, the bridge circuit drive system switching condition due to the influence of noise of the motor current detection value or the like is changed. There is an effect that erroneous determination can be prevented.

According to the twelfth aspect of the invention, since the bridge circuit driving system is switched only for a predetermined time after the bridge circuit driving system switching condition is satisfied, an increase in heat generation of the switching element due to the switched bridge circuit driving system is almost ignored. Further, there is an effect that it is possible to prevent the controllability of the current from deteriorating due to hunting of switching of the bridge circuit driving method.

According to the thirteenth aspect of the present invention, after switching the bridge circuit driving method, the motor control in the driving method is continued until the switching element driving duty ratio becomes equal to or higher than the fourth predetermined value. There is an effect that it is possible to suppress hunting of the switching and deterioration of current controllability.

According to the fourteenth aspect of the present invention, since the bridge circuit driving method is the three-phase bridge circuit driving method, the overcurrent of the motor current is prevented as well as the motor current as in the single-phase bridge circuit driving method. This has the effect of suppressing current overshoot and hunting.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the first embodiment of the present invention.

FIG. 3 is a characteristic diagram for determining a motor current target value according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a case where an overcurrent of a motor is suppressed in the first embodiment of the present invention.

FIG. 5 is a diagram showing a switching element drive waveform when a single-phase double-sided chopper system is energized in the right direction.

FIG. 6 is a diagram showing a switching element drive waveform when a target current is 0 in a single-phase single-sided or single-phase double-sided chopper method.

FIG. 7 is a diagram showing a switching element drive waveform when a left-side current is applied in a single-phase double-sided chopper method.

FIG. 8 is a diagram showing a switching element drive waveform when a single-phase one-sided chopper system is energized in the right direction.

FIG. 9 is a diagram showing a switching element drive waveform when a single-phase one-sided chopper system is energized in the left direction.

FIG. 10 is a configuration diagram showing a second embodiment of the present invention.

FIG. 11 is a flowchart for explaining the operation of the second embodiment of the present invention.

FIG. 12 is a diagram showing a switching element drive waveform when a two-phase double-sided chopper system is energized in the right direction.

FIG. 13 is a diagram showing a switching element drive waveform when a two-phase double-sided chopper system is energized in the right direction.

FIG. 14 is a diagram showing switching element drive waveforms when the target current is 0 in the two-phase double-sided chopper method.

FIG. 15 is a flowchart for explaining the operation of the third embodiment of the present invention.

FIG. 16 is a flowchart for explaining the operation of the fourth embodiment of the present invention.

FIG. 17 is a flowchart for explaining the operation of the fifth embodiment of the present invention.

FIG. 18 is a flowchart for explaining the operation of the sixth embodiment of the present invention.

FIG. 19 is a diagram for explaining a motor current path according to a single-phase, single-sided chopper method.

FIG. 20 is a diagram for explaining a motor current path according to a single-phase double-sided chopper method.

FIG. 21 is a diagram showing a case where an overcurrent flows through the motor in a single-phase one-sided chopper system.

FIG. 22 is a diagram showing a case where an overcurrent of a motor is suppressed by a conventional device.

[Explanation of reference numerals] 1 vehicle-mounted battery, 2 motors, 3a to 3d switching elements, 5 bridge circuits, 8 motor current detection means, 9 switching element drive circuits, 11, 11A drive method switching means, 13 control means, 20 torque detection means , 21 Vehicle speed detection means.

Continuation of the front page (56) Reference JP-A-8-336293 (JP, A) JP-A-9-37584 (JP, A) JP-A-56-58783 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H02P 5/00-5/26 H02P ^7/ 00-7/34

Claims (14)

(57) [Claims] 1. A motor current detection means for detecting a current of a motor connected to a bridge circuit as a load, and a current feedback control from a motor current detection value and a motor current target value to drive a switching element of the bridge circuit. A switching element driving means for calculating the duty ratio and driving the switching element,
If the switching element drive duty ratio is less than or equal to a first predetermined value, the drive method for driving the switching element is a bridge circuit drive method for regenerating a motor current to a power source. 2. The bridge circuit drive system is composed of a plurality of drive systems having different regenerative current controllability, and when the motor current is controlled, the switching element drive duty ratio is not more than a first predetermined value. The motor control device according to claim 1, wherein the drive system is switched to a drive system having better controllability of regenerative current. 3. The motor control device according to claim 2, wherein a single-phase single-sided chopper system and a single-phase double-sided chopper system are used as the plurality of drive systems. 4. The motor control device according to claim 2, wherein a single-phase single-sided chopper method and a two-phase double-sided chopper method are used as the plurality of drive methods. 5. In the single-phase one-sided chopper method, a bridge circuit is composed of four sets of switching elements, and one of a pair of switching elements in the flow direction is driven by a pulse width modulated signal, and the other of the pair of switching elements. The motor control device according to claim 3 or 4, wherein the switching element is continuously driven to be turned on, and the pair of switching elements that are not in the flow direction are turned off. 6. In the single-phase double-sided chopper method, a bridge circuit is composed of four sets of switching elements, and a pair of switching elements in the flow direction are driven by a pulse-width-modulated drive signal, and a pair not in the flow direction 4. A driving method for turning off the switching element of 1.
The motor control device according to. 7. In the two-phase double-sided chopper method, a bridge circuit is composed of four sets of switching elements, and a pair of switching elements in the flow direction are driven by a pulse width modulated drive signal, and a pair not in the flow direction. 5. The motor control device according to claim 4, wherein the switching element is driven by a signal obtained by inverting the drive signal. 8. The motor control device according to claim 1, wherein if the degree of change of the motor current is not less than a second predetermined value, the bridge circuit driving method is switched. 9. The motor control device according to claim 1, wherein if the degree of change in the switching element drive duty ratio is not less than a third predetermined value, the bridge circuit drive method is switched. . 10. The degree of change in the deviation of the motor current is third.
The motor control device according to any one of claims 1 to 7, wherein the bridge circuit driving method is switched when the value is equal to or more than a predetermined value. 11. The motor control device according to claim 1, wherein the bridge circuit drive system is switched when the bridge circuit drive system switching condition continues for a predetermined time. 12. The motor control device according to claim 1, wherein the bridge circuit drive system is switched only for a predetermined time after the bridge circuit drive system switching condition is satisfied. 13. The motor control according to any one of claims 1 to 11, wherein after switching the bridge circuit drive system, the motor control in the drive system is continued until the switching element drive duty ratio becomes equal to or more than a fourth predetermined value. The motor control device described in (1). 14. The motor control device according to claim 1, wherein the bridge circuit driving method is a three-phase bridge circuit driving method.