JPH10271884A - Controller for permanent magnet synchronous motor and controller for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out three-phase short-circuit processing at the time of a restart at a time when a permanent magnet synchronous a rotor is rotated at high speed without flowing of an overcorrect through a switching element at the time of the initial stage of a three-phase short circuit. SOLUTION: The controller for the permanent magnet synchronous motor has an inverter 2 having pairs of switching elements to the three phase of the permanent magnet synchronous motor having three phase respectively and supplying the motor 1 with AC power converted from DC power, a filter capacitor 3 being connected in parallel with a inverter 2 and filtering DC power, and a control section 11 controlling the driving of the motor 1 by on-off controlling etch switching element 20-25 of the inverter 1, and has a short-circuit transfer processing section 13, etc., transferring to a three-phase short circuit after the precedent on-off control of each switching element 20-25 is executed so as to avoid an overcorrect generated at an initial stage at a time when three- phase short circuit is conducted at the time of the revolution of the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device used for a permanent magnet type synchronous motor and a control device for an electric vehicle using the control device.

[0002]

2. Description of the Related Art As a control device for a permanent magnet type synchronous motor, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 6-315201. According to the disclosed technology, when the control of the permanent magnet synchronous motor is started when the permanent magnet synchronous motor is rotating at a high speed, or when the rotational speed of the permanent magnet synchronous motor exceeds the controllable range due to excessive increase. In such a case, when the switching element of the inverter is in the off state, a high DC voltage is generated on the input side of the inverter due to the power generation operation of the permanent magnet motor. Therefore, if the battery and the inverter are connected by a relay circuit in order to start or restart the control of the permanent magnet synchronous motor, the battery will be overcharged. Therefore, a contactor that opens the connection between the inverter and the permanent magnet type synchronous motor is provided, and when the power supply to the pre-drive circuit that drives the inverter switching is cut off, the connection between the inverter and the permanent magnet type synchronous motor is cut off. To prevent the appearance of the input side of the inverter of high DC voltage due to the power generation operation of the permanent magnet type synchronous motor.

[0003] The technique disclosed in Japanese Patent Application Laid-Open No. 6-315201 has a problem that the cost increases and the weight increases because a contactor is used.

According to Japanese Patent Application Laid-Open No. Hei 1-190286, a three-phase switch that simultaneously turns on at least two of three switching elements connected to the negative electrode side of a DC power supply among six switching elements of an inverter is disclosed. There is disclosed a technique in which a braking force is generated in a permanent magnet motor by a short circuit to perform stop maintaining control.

The technique disclosed in Japanese Patent Application Laid-Open No. 1-190286 is a control at the time of stoppage, not at the time of running. Therefore, when the permanent magnet type synchronous motor is rotating at high speed, a three-phase short circuit is performed. However, there remains a problem in that a large current flows from the motor to the switching element of the inverter at an initial stage (transiently), and there is a disadvantage that using a switching element having a large maximum allowable current causes an increase in cost.

Here, a case where a three-phase short circuit is required in a control device for a permanent magnet type synchronous motor performing an on / off control operation will be described with reference to FIG. FIG.
FIG. 4 is a diagram illustrating motor current and motor torque characteristics when a phase short circuit is performed.

To control the three-phase short circuit, all the switching elements 20, 22, and 24 connected to the positive side of the DC power supply are turned on, and all the switching elements 21, 23 and 23 connected to the negative side of the other DC power supply are turned on. This can be achieved by outputting a signal for turning off 25 from the control unit 11. By this control, the current of the three-phase terminal of the motor 1 is changed to the switching element 2
Flowing through the 0, 22, 24 and associated diodes, the three phase terminals of the motor 1 will be physically coupled.

The three-phase short circuit is caused by switching element 21,
23, 25 turned on, switching elements 20, 22, 24
Off is also achieved.

However, when a three-phase short circuit is simply performed, the following problem occurs. At time 0, the other switching element is turned on at the same time without any contrivance.
FIG. 10 (a) shows the U-phase current, FIG. 10 (b) shows the V-phase current, and FIG. 10 (b) shows the characteristics of the motor current and the motor torque when the phase is short-circuited (the other switching element remains off). FIG. 10C shows the W-phase current, and FIG. 10D shows the torque characteristics.

The characteristics shown here are as follows. First, the U-phase current is largely biased toward the positive side, and the V-phase and W-phase currents are biased toward the negative side. Both the V-phase and the W-phase settle down into a sine wave centered at 0. At this time, the motor torque also has a torque fluctuation that leads to vibration. Depending on the position of the magnetic pole of the permanent magnet at the start of the three-phase short-circuit, the characteristic of the motor current being biased at the start of the three-phase short-circuit is that the V-phase is the most biased, the W-phase is the most biased, or the positive side. This is because they are biased toward the negative side.

[0011]

In the prior art, 3
FIG. 1 shows the phenomenon that the motor current is biased at the start of the phase short circuit.
1 and FIG. FIG.
It is a figure explaining the motor equivalent circuit in case of 0. FIG.
FIG. 3 is a diagram illustrating motor current-time characteristics when a three-phase short circuit is performed.

FIG. 11A is a diagram showing an equivalent circuit of a permanent magnet type synchronous motor during a three-phase short circuit. Where Ra is the armature winding resistance, La is the armature winding self-inductance, e
u, ev, and ew are induced voltages by the permanent magnet. FIG. 11 (a)
Current flowing in the equivalent circuit (called steady-state current component)
Is shown in FIG. FIG. 11B is a diagram showing an equivalent circuit of the motor excluding the induced voltage by the permanent magnet. FIG. 4B shows a current (referred to as a transient current component) flowing through the equivalent circuit of FIG. 11B. The current when the three-phase short circuit is performed can be expressed as the sum of the steady-state current component in FIG. 4A and the transient current component in FIG.

The steady-state current component shown in FIG. 4A is a current characteristic (sine wave of amplitude i1) for one phase (U phase) when a sufficient time has elapsed after the start of the three-phase short circuit. Although not shown,
Assuming that the frequency of the current is very high, the induced voltage eu is generated at a phase that is approximately 90 ° ahead of the current. The bias of the current at the start of the three-phase short circuit changes depending on which phase of the steady-state current component is at the timing of the start of the three-phase short circuit.

That is, in the steady-state current component shown in FIG.
When the three-phase short circuit is started at the timing of the phase at the point (1), the current starts to flow without biasing either positive or negative. When the three-phase short circuit is started at the timing of the phase of the point (2), the current starts to flow unevenly below the switching element connected to the negative electrode side, and the three phases are shorted at the timing of the phase of the point (3). When the short circuit starts (corresponding to the illustration in FIG. 10A), the current starts to flow unevenly to the switching element connected to the positive electrode side.

This is because the current is 0 before the three-phase short circuit starts, and when the three-phase short circuit starts at the timing of the phase at the time (2), the current starts to flow from 0 to the minus side,
Thereafter, it flows to a magnitude twice as large as the amplitude of the sine wave. Likewise
When the three-phase short circuit starts at the timing of the phase at the time point (3), the current starts to flow from 0 to the positive side, and then flows to twice the amplitude of the sine wave. Therefore, if a three-phase short circuit is started at the timing of the phase at the time of (1),
For one phase (U phase), there is no bias, but V phase, W phase
The phases are delayed by 120 ° and 240 ° from the U phase, respectively, so it is not possible to eliminate the bias of all three phases.

On the other hand, the transient current component shown in FIG. 4 (b) indicates the current bias at the start of the three-phase short circuit. iu ′ is a biased U-phase current component (three-phase short-circuit transient current component), and attenuates with a time constant τ represented by equation (1). τ = La / Ra (Equation 1) The three-phase short-circuit transient current component of the V-phase W-phase also attenuates with the time constant τ.

Further, the three-phase short-circuit transient current component iu ′ can be expressed by the following equation (2). iu ′ = iu′0 · exp (−t / τ) (Equation 2) The initial value iu′0 of this attenuation curve is the current value of the phase at which the three-phase short circuit has started in the steady-state current component of FIG. When a three-phase short circuit is started at the timing of the inverted signal, that is, at the timing of the phase (2), the initial value iu′0 is −i1 and in the case of (3), it is i1. Similarly, the initial values of the V-phase and W-phase three-phase short-circuit transient current components are obtained by inverting the signs of the current values of the phases at which the three-phase short-circuit is started in the V-phase and W-phase steady current components, respectively.

If the current flowing at the start of the three-phase short circuit exceeds the maximum current value of the switching element (IGBT or the like), the switching element may be broken. FIG. 10 (d)
It is conceivable that the motor torque fluctuates as shown by the torque characteristics of FIG.

An object of the present invention is to provide a control device for a permanent magnet type synchronous motor and a control device for an electric vehicle, which avoid the occurrence of an excessive current and reduce the cost.

[0020]

SUMMARY OF THE INVENTION A feature of the present invention is to provide an inverter for supplying AC power converted from DC power to a three-phase permanent magnet type synchronous motor through a switching element provided for each phase, and the inverter. And a control unit for controlling the inverter by performing on / off control of each of the switching elements including a three-phase short circuit of the permanent magnet type synchronous motor. A control device for a magnet-type synchronous motor, wherein before the control unit performs the on-off control of the three-phase short-circuit when the permanent magnet-type synchronous motor rotates, the control unit executes a preceding on / off control of each switching element, And a short-circuit shifting means for shifting to the three-phase short-circuit.

Another feature of the present invention is that the inverter constitutes a three-phase bridge circuit by at least six of the switching elements, and the short-circuiting transition means is provided when all of the switching elements are off. The switching element for one phase or two phases connected to the positive side of the DC power supply and the switching elements for the other phases connected to the negative side of the DC power supply are turned on at a predetermined time determined by the state of the motor. A permanent magnet type synchronous motor control device that switches to an on-off state of the switching element and shifts to a three-phase short circuit after a predetermined period for suppressing a transient current in a state.

Another feature of the present invention is that in a control device for a permanent magnet synchronous motor which switches a rotating three-phase permanent magnet synchronous motor from a free-run state to a drive by an inverter, a control is provided by a magnetic pole position of the permanent magnet synchronous motor. A permanent magnet synchronous motor control device which performs switching control for canceling a transient current caused by a three-phase short circuit by the inverter from a predetermined point in time.

A control device for an electric vehicle which achieves the above object is controlled by using the control device for a permanent magnet type synchronous motor.

Furthermore, the control device for an electric vehicle includes a phase selecting means for selecting a phase of a switching element through which a transient current component generated by the rotating three-phase permanent magnet type synchronous motor flows, and a phase selecting means for the selected phase. And a canceling control means for applying the stored power of the smoothing capacitor for a predetermined period so as to cancel the transient current component.

According to the present invention, the prior control is executed when the permanent magnet type synchronous motor rotates, and the process shifts to the three-phase short circuit, so that the occurrence of an excessive current is prevented. That is, the three-phase short-circuit processing at the time of restarting when the permanent magnet type synchronous motor is rotating at high speed can be performed without causing an excessive current to flow through the switching element at the beginning of the three-phase short-circuit. Thereby, the switching element can be prevented from being broken, which is effective in improving the safety of the control device for the permanent magnet type synchronous motor at the time of high speed rotation.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a control device for a permanent magnet type synchronous motor according to an embodiment of the present invention (hereinafter, also simply referred to as a control device). The control device for a permanent magnet type synchronous motor according to the present embodiment includes an inverter 2 for supplying AC power to a permanent magnet type synchronous motor 1 (hereinafter also abbreviated as a motor 1) and a smoothing capacitor 3 (hereinafter abbreviated as a capacitor 3). ), And a control unit 11. The control device further includes a magnetic pole position sensor 4 for detecting a magnetic pole position, an encoder 5, a current sensor 6, a main relay 7,
An auxiliary relay 8, a resistor 9, and a battery 10 are provided.

The control unit 11 includes a current control unit 12, a short-circuit transition processing unit 13, a voltage command switching unit 14, and a carrier wave comparison unit 1.
5, a PWM signal output permission section 16 and the like. The control unit 11 further has a function of controlling on / off of the main relay 7 and the auxiliary relay 8. Control unit 11
Can be composed of, for example, a microcomputer and a program for executing processing of various functions.

Here, a method of controlling the permanent magnet type synchronous motor of the permanent magnet type synchronous motor control device of the present embodiment will be described. That is, a method of controlling the speed and torque of the permanent magnet type synchronous motor by controlling the power supplied to the motor by turning on and off the switching element of the inverter will be described.

The control section 11 turns on the auxiliary relay 8 to charge the capacitor 3 from the battery 10 as a process before starting the switching control of the inverter 2. Here, the main relay 7 is turned off. The maximum value of the charging current to the capacitor 3 can be suppressed by the resistor 9, and burning of the relay and the wiring can be prevented. When the voltage of the capacitor 3 becomes equal to the voltage of the battery 10, the main relay 7 is turned on. The auxiliary relay 8 turns off.

After the main relay 7 is turned on, the control section 11 starts the current control section 12, and the resulting three-phase
The voltage command value of (U phase, V phase, W phase) is output to the inverter 2 as a PWM signal. The current controller 12 compares the torque component current command and the excitation component current command with the torque component current and the excitation component current obtained from the current value output from the current sensor 6 to calculate a voltage command. The current command is calculated from the torque command, the motor rotation speed, and the like by vector control or the like.

In an electric vehicle controller or the like, a torque command is obtained from the accelerator opening and the like. Calculate motor speed control,
A torque command may be obtained. The magnetic pole position necessary for current control is determined by a magnetic pole position sensor 4 as a magnetic pole position detecting means.
Calculate based on the signal from Motor speed (motor speed)
Is obtained from the pulse output from the encoder 5.

The voltage command switching section 14 selects a voltage command obtained by current control and outputs the selected voltage command to the carrier comparison section 15. The carrier comparison unit 15 compares the three-phase voltage command with the carrier, and creates a PWM signal for each of the three phases. Here, the carrier comparison unit 15 may use a timer unit or the like built in the microcomputer. The PWM signal output permission section 16 is where the PWM signal output to the gate section of the inverter 2 is prohibited or permitted. If the output of the PWM signal is permitted, the switching operation of the inverter 2 is performed by the PWM signal. If prohibited, all switching elements are turned off.

The PWM signal output permitting section 16 may use a PWM signal output stop function built in the microcomputer provided in the control section 11 (or the control device itself).
An external circuit that outputs an output permission control signal from the microcomputer and performs an AND operation with the PWM signal may be employed.

When the rotational speed of the motor exceeds the controllable range, the control unit 11 stops the current control unit 12 and prohibits the output of the PWM signal by the PWM signal output permitting unit 16. Switching element 20, 2 of inverter 2
1, 22, 23, 24 and 25 are all turned off. At this time, the induced voltage of the motor 1 appears on the input side of the inverter 2 through the diode circuit of the inverter 2.

Therefore, in order to prevent the battery 10 from being overcharged by the induced voltage of the motor 1, the control unit 11
Performs a control to turn off the main relay 7 and disconnect the battery 10 and the inverter 2. That is, the inverter 2
The short-circuit control of the three-phase terminals of the motor 1 (control referred to as three-phase short-circuit) is executed so that each relay can be turned on again so that no induced voltage appears on the input side of the motor. When the three-phase short circuit is being performed, the auxiliary relay 8 is turned on, and the main relay 7 is turned on. The unit 12 is restarted.

In the following cases, a control process for controlling a three-phase short circuit is required. That is, while the motor 1 is rotating at high speed,
For example, when the control power (not shown) of the control unit 11 of the control device is turned off due to an unexpected factor while the electric vehicle is running, in other words, when the on / off control is suddenly stopped, the control unit 11 , The main relay 7 and the auxiliary relay 8 are turned off, and all the switching elements of the inverter 2 are turned off. Then, when the operator of the control device (the driver of the electric vehicle) turns on the control power source, turns on the auxiliary relay 8 as usual, and restarts the control device, a high induced voltage is generated on the input side of the inverter 2. Therefore, the relay circuit (a circuit including only the main relay 7 or a circuit including the main relay 7 and the auxiliary relay 8) may be burned or the battery may be overcharged. Therefore, in order to improve the reliability, it is necessary to perform a three-phase short-circuit control process of the motor 1 before turning on the relay.

To control the three-phase short-circuit, the control unit 11 simultaneously turns on the switching elements 20, 22, and 24 connected to one side of the inverter 2, for example, the positive side of the DC power supply, and turns on the negative side of the DC power supply. Each of the connected switching elements 21, 23, 25 outputs a signal that is kept off,
Perform a three-phase short circuit. Alternatively, a signal is output in which the switching elements 21, 23, 25 are simultaneously turned on and the switching elements 20, 22, 24 are kept off,
Perform a three-phase short circuit. By this control, all the currents at the three-phase terminals of the motor 1 flow through the switching elements 20, 22, and 24 and the associated diodes, or flow through the switching elements 21, 23, and 25 and the associated diodes. Is the same as physically combining

The feature of the control processing according to the present invention is that, at the start of the three-phase short circuit, the transient current component generated when the three-phase short circuit is simply performed without any contrivance is stored in the storage power held by the smoothing capacitor 3 in FIG. Is canceled by supplying a current to the motor based on the above.

Next, the short-circuit control processing according to the present invention will be described with reference to the flowchart of FIG. To perform this control process,
First, in the calculation unit 17 of the application time of the capacitor voltage of the short-circuit transfer processing unit 13 of the control unit 11, the smoothing capacitor 3
(S201), and then the calculation of the application time of the capacitor voltage (a predetermined period T1 described later) is executed (S201).
202). This is because the magnitude of the current flowing through the motor 1 based on the stored power held by the capacitor 3 is determined by the voltage of the capacitor 3 and the time during which the switching element is turned on.

When the application time of the capacitor voltage is determined, the short-circuit voltage command calculator 18 calculates the short-circuit voltage command accordingly (S203). This is the required capacitor voltage application time (pulse width) after comparing with the carrier.
The voltage command is calculated so that is obtained.

Here, it is assumed that the voltage command switching unit 14 selects the voltage command of the short circuit transition processing unit 13. next,
The short-circuit signal output timing detecting section 19 detects the “first timing” as a predetermined time point for the preceding on / off control (S204), and performs the PW operation for the preceding on / off control.
A PWM signal output permission signal is output to the M signal output permission unit 16 (S205). Short circuit signal output timing detector 19
Determines the first timing (phase) of applying the capacitor voltage from the magnetic pole position so that the phase in which a large transient current component flows is determined in advance to cancel the transient current component.
It outputs an M signal output permission signal. Then, after a lapse of a predetermined time T1, the control shifts to the three-phase short-circuit control (S20).
6, S207).

The operation of this embodiment when the largest transient current component flows in the U phase as shown in FIG. 10 will be described with reference to FIG. At the timing of time t0 to be described later, as shown in FIG.
Is turned on, and the other switching elements 21, 22, 24 are turned off. Next, when the predetermined time T1 has elapsed, FIG.
As shown in (B), the on / off state of the U-phase switching element is switched. That is, the switching element 20 is turned off and the switching element 21 is turned on. As a result, all the switching elements on the negative side of the DC power supply are turned on, so that the motor 1 is short-circuited in three phases.

Before shifting to the three-phase short-circuit state, FIG.
By configuring the circuit for only the predetermined time T1, the pulse voltage VPU of the capacitor voltage Vc as shown in FIG. 6 and the period T1 is applied to the U phase. Therefore, according to the theorem of “the principle of superposition of electric circuits”, the current flowing in each phase is a steady current component due to the induced voltage of the motor 1, a compensation current component due to the pulse voltage VPU generated in the operation of FIG. It is expressed by the sum of the phase short-circuit transient current components.
That is, it is the sum of the steady-state current component shown in FIG. 11, the three-phase short-circuit transient current component, and the compensation current component shown in FIG. Accordingly, a large current is prevented from flowing by canceling the three-phase short-circuit transient current component with the compensation current component.

As can be seen from FIG. 6, when the circuit constant of each phase is the same, the compensation currents of the V-phase and W-phase flowing by the pulse voltage VPU have the same value. Therefore, in order to compensate for the three-phase short-circuit transient current component in the present embodiment, the condition is that the three-phase short-circuit transient currents of the V phase and the W phase are equal.

Therefore, what is important in this series of operations is a method of determining a time t0 at which control is started and a predetermined time T1. At time t0, the timing of the induced voltage at which the absolute value of the steady current becomes maximum is set. Specifically, U in FIG.
It is time (3) when the steady-state current of the phase becomes maximum. At this time,
The V-phase and W-phase steady-state currents are half (but the signs are opposite) of the U-phase currents and have the same value, and thus satisfy the above-described conditions. Details will be described with reference to FIG.

Since the three-phase short-circuit transient current component differs depending on the phase at which the three-phase short circuit starts, the first timing for applying the pulse voltage is set as follows. FIG. 8 is a diagram showing a first timing of one embodiment according to the present invention. FIG. 8 shows the steady-state current components of the U phase, the V phase, and the W phase, and the induced voltage components of the U phase. Steady-state current components (iu, iv, iw) have the same amplitude i1 and a phase of 120 °
Are off by one. The induced voltage (only eu is shown) is generated by a change in the magnetic flux of the permanent magnet interlinking with the stator winding of the permanent magnet type synchronous motor, and the phase of the induced voltage is, for example, a permanent magnet type synchronous motor. Can be obtained from the magnetic pole position detected by the existing magnetic pole position detecting means.
Here, since the motor current is assumed to be in a high frequency region, the phase difference between the induced voltage and the current is substantially 90 °.

In the phase shown by the vertically drawn dotted line in FIG. 8, the V-phase current and the W-phase current are equal in amplitude (i1 / 2), and the amplitude of the U-phase current (-i1) The sign is opposite, and the size is halved. If a normal three-phase short-circuit is started at the phase at this point, the initial value of the U-phase three-phase short-circuit transient current becomes “i1”, and the initial value of the V-phase and W-phase three-phase short-circuit transient current becomes “−i”. 1/2 ”.

Next, a method for determining the predetermined time T1 will be described with reference to FIGS. As described above, FIG.
The pulse voltage V generated when the control as shown in FIG.
FIG. 6 shows an equivalent circuit for determining a compensation current component of each phase flowing through the PU. The compensation current component iu "flowing in the U-phase by the pulse voltage VPU has a waveform as shown in FIG. 7. During a predetermined period T1 after the pulse voltage is generated, the U-phase compensation current component iu" is expressed by (Equation 3). ), (Equation 4) increase in the negative direction by the given equation.

Iu "= − i2 · {1-exp (−t / τ)} (Equation 3) i2 = 2Vc / (3Ra) (Equation 4) where time constant τ = La / Ra. The V-phase compensation current component iv "and the W-phase compensation current component iw" are given by iv "= iw" =
−iu ”/ 2.

Here, there is a point in time when the absolute values of the U-phase compensation current component iu "and the three-phase short-circuit transient current component iu 'flowing in the U-phase are coincident, so that (Expression 3) ) Is used to determine the predetermined time T1.If the time constant τ is large, it can be determined by linear approximation.An example of a specific method for determining the predetermined time T1 will be described below.

The first timing as the predetermined time is U
If the phase is captured and expressed, the switching elements 20, 23, 2
5 are simultaneously turned on, it is an inflection point where the di / dt of the steady-state current component shifts from negative to positive.

The switching elements 21, 22, 24
Is the inflection point at which di / dt transitions from positive to negative. Then, as described above, the inflection point can be obtained in advance from the phase position detected by the magnetic pole position detecting means.

On the other hand, the predetermined period T1 during which the pulse voltage is applied by the capacitor is a three-phase short-circuit transient current component iu '(initial value i1) shown in FIG.
This is the time when the sum with iu '' becomes zero (0). Therefore, when this time is calculated by solving the equation, T1 = −τ · ln (i2 / (i2 + i1)) (5)

Since i2 is a function of the capacitor voltage, it is necessary to calculate the predetermined period T1 based on the capacitor voltage. Since it takes a long processing time to calculate the predetermined period T1 by a microcomputer, for example, it is desirable to create a table in which the predetermined period T1 according to the capacitor voltage is calculated in advance and use this table. That is, another feature of the present invention resides in that the predetermined period T1 is changed according to the magnitude of the voltage of the smoothing capacitor. In other words, there is provided means for detecting the voltage of the smoothing capacitor and calculating the predetermined period T1.

Although it is not possible to correct the bias of the 100% current, the predetermined period T1 is fixed to an "appropriate value", and the switching element (for example, IG
It is also possible not to break BT).

Further, in this embodiment, the first timing is set accurately.
In the sampling process of the microcomputer, it can be said that it is difficult to accurately detect the phase at the time shown in FIG. Therefore, the predetermined period T1 during which the pulse voltage is applied has a certain amount of time width. Therefore, as the first timing, a time width of about the predetermined period T1 is provided before and after the phase shown in FIG. In other words, even if a time point within a predetermined area set before and after the inflection point (for example, an area having the same time width T1 as the predetermined period T1 before and after the inflection point) is adopted, the same applies. The effect of can be obtained. Furthermore, a predetermined period T1
Even in a predetermined area having a time width (2T1) about twice as large as before and after the inflection point, the overcurrent causes the switching element to function as a switching element.
It has been confirmed that it has the effect of preventing IGBT from being broken. Incidentally, the time width of this embodiment is T1 = 150 (μsec)
It is about.

As shown in FIG. 3, when the switching element is switched for a predetermined time T1 calculated from the capacitor voltage Vc or the like, after the predetermined time T1 has elapsed, the pulse voltage VPU
Becomes 0. Therefore, the compensation current components iu ", i
v "and iw" gradually decrease to 0 with a time constant τ as shown in FIG. If the absolute value of the U-phase compensation current component iu "and the three-phase short-circuit transient current component iu 'flowing in the U-phase are the same after the lapse of the predetermined time T1, the waveform after the lapse of the predetermined period T1 in FIG. The sign is different from that of the three-phase short-circuit transient current component of b), but the waveform is the same, that is, the U-phase compensation current component iu "and the three-phase short-circuit transient current component iu 'flowing in the U phase after a predetermined time T1 has elapsed.
The predetermined time T1 is determined so that the absolute values of the three phases coincide with each other, so that the three-phase short-circuit transient current component of each phase can be canceled by the compensation current component of each phase. Therefore, only the steady current component of FIG. 4A flows.

Conversely, the other switching element 21
It is also conceivable that one of the switching elements 22 and 24 is turned on at the same time.
(Phase) is shifted by 180 ° from the case where the switching elements 20, 23, 25 are turned on.

Then, after a predetermined period, one of the switching elements 22 and 24 is turned off and the other switching elements 23 and 25 are turned on to shift to a three-phase short circuit. At this time, the current from the capacitor 3 is transmitted from the switching elements 22 and 24 to the switching element 21 through the motor 1.
Flows to

Further, the switching elements 20, 2
After turning on the switches 3 and 25 at the same time or turning on the switching elements 21, 22 and 24 at the same time, one of the switching elements 20, 22 and 24 may short-circuit three phases.

When the largest transient current component flows in the V-phase and the current is to be canceled, the switching elements 21, 22, and 25 are turned on at the same time, and after a predetermined period, the switching element 22 is turned off and switched. A method similar to that in the case of the U phase, such as turning on the element 23 and shifting to a three-phase short circuit, can be considered. In the case where the largest transient current component flows in the W phase and the current is to be canceled, the switching elements 21, 23 and 24 are simultaneously turned on, and after a predetermined time,
The same method as in the case of the U phase, such as turning off the switching element 24 and turning on the switching element 25 to shift to a three-phase short circuit, can be considered.

As described above, the on / off of the switching element can be arbitrarily selected in relation to the induced voltage.
Therefore, when the motor control by the inverter is restarted from the state in which the motor 1 is rotating in the free-running mode, if the time until the restart is required to be as short as possible, the state of the induced voltage is set so that a large transient current does not flow. It is desirable to determine the on / off state of the three-phase switching element from the above-described switching methods in accordance with the following.

In the case of a product that does not cause a problem even if it takes several tens to several hundreds of milliseconds until the motor control is restarted, the switching method can be determined in advance as shown in FIG. In that case, as shown in FIG.
It is also possible to determine the timing at which the U-phase steady-state current component becomes negative and maximum from the induced voltage of the phase, and to start the control with that time as t0.

The above description is the three-phase short-circuit pre-control during rotation according to the present invention for preventing a large current from flowing through the switching element.

The control device according to the present invention executes leading ON / OFF control of each switching element in order to avoid an excessive current generated at the initial stage when the three-phase short circuit is performed when the motor 1 is rotating, and the three-phase short circuit is performed. Short-circuit transfer means (that is, constituent means of short-circuit transfer processing unit 13 or short-circuit transfer processing unit 1)
3, voltage command switching unit 14, carrier comparison unit 15, and P
WM signal output permission unit 16 and the like). According to the present invention, it is possible to introduce three-phase short-circuit control during rotation, and it is possible to avoid generation of an excessive current without using a switching element or a contactor having a large maximum allowable current, leading to cost reduction and improvement in reliability. The effect is obtained.

FIG. 5 is a diagram showing motor torque characteristics when the control of the present embodiment shown in FIGS. 2 and 3 is performed. FIG. 5 shows that the maximum current flowing in each phase is reduced by half compared with the characteristic of FIG. 10 when a three-phase short circuit is performed by the conventional control. All the three-phase currents are not biased to the positive side / negative side, and only the sinusoidal steady-state current component flows immediately after the start of the control. That is, it shows that the three-phase short-circuit transient current component is canceled by the compensation current component. Also, almost no transient motor torque fluctuation occurs.

Next, a method of outputting a pulse voltage by a capacitor by comparing carrier waves and shifting to a three-phase short circuit will be described.

FIG. 9 is a diagram showing a method of applying a capacitor voltage by comparing carriers according to an embodiment of the present invention.
That is, an embodiment of the short-circuit transition means that outputs a pulse voltage while also using a function of outputting a PWM signal by a counter or the like built in the microcomputer is shown. Note that the short-circuit transfer means of the present embodiment includes a short-circuit transfer processing unit 13, a voltage command switching unit 14, a carrier wave comparison unit 15, and a PWM signal output permission unit 16. Hereinafter, this will be described.

In FIG. 9, the clock is counted to 0
There are two counters that repeat up and down between and datamax, and the U-phase, V-phase, and W-phase voltage values datau, datav, and dataw
Can be automatically output six PWM signals to drive the U-phase, V-phase, and W-phase switching elements by setting the value in a dedicated register and comparing the values of the counter and the register. It is. By making a comparison with the two counters, a short-circuit prevention time for the upper and lower switching elements is created. When the current control is performed, a voltage value obtained by calculating the current control is set in a register, a PWM signal is output, and the inverter is operated by the PWM signal to drive the motor.

When shifting to a three-phase short circuit using this function, for the U phase, as shown in FIG. 9A, the voltage command datau is set to zero (0) before the output of the PWM signal is permitted. The signal of the upper arm is turned on, and the signal of the lower arm is turned off. The signal of the upper arm operates to turn on and off the switching element 20 of FIG. 1 when the PWM signal output is permitted, and the signal of the lower arm operates to turn on and off the switching element 21 of FIG.

For the V phase and the W phase, as shown in FIG. 9B, the voltage commands datav, d are issued before the output of the PWM signal is permitted.
Ataw is set to the value of datamax, the signal of the upper arm is turned off, and the signal of the lower arm is turned on. When the output of the PWM signal is permitted, the signal of the upper arm operates to turn on and off the switching elements 22 and 24 of FIG. 1, and the signal of the lower arm operates to turn on and off the switching elements 23 and 25 of FIG.

Next, in order to output a pulse voltage from the capacitor at the phase (first timing) shown by the broken line in FIG. 8, that is, to enable the PWM signal output, the permanent magnet type synchronous motor The magnetic pole position is determined. This determination process is a process (not shown) that is started repeatedly in synchronization with the counter of FIG. 9 every cycle or every half cycle of the counter. In the above determination processing, when it is determined that the phase (first timing) indicated by the broken line in FIG.
The M signal output is permitted. When the PWM signal output is permitted, a preset U-phase, V-phase, and W-phase upper arm signal and a lower arm signal are transmitted to the respective switching elements, and the switching elements 20, 23, and 25 are turned on.
Switching elements 21, 22, 24 remain off. (When the PWM signal output is prohibited, all the switching elements are turned off.) The above state is a state in which a pulse voltage is applied based on the power from the capacitor 3 and the pulse voltage is set to a predetermined value. After the addition of the period T1, the switching element 20 needs to be turned off and the switching element 21 needs to be turned on.
In FIG. 9 (a), a predetermined period T1 according to the capacitor voltage is calculated in advance, and the application time of the pulse voltage is set to the predetermined period T1.
The voltage command datau is changed to be 1. This process is also performed as part of a process that is repeatedly started every cycle or every half cycle of the counter in synchronization with the counter, and the voltage command datau is changed at points A and B.

After the PWM signal output is permitted, A
The time to the point is checked in advance, and the voltage at the point A is calculated so that the pulse voltage finally reaches a predetermined period T1. B
At this point, the voltage datau is set to the value of datamax, the signal of the upper arm is turned off, and the signal of the lower arm is turned on, that is, the switching element 20 is turned off and the switching element 21 is turned on, and the three-phase short circuit is started.

Here, depending on the size of the predetermined period T1, the voltage command is not changed at the point A, but is changed to 0 at the point B.
Setting the voltage datau between to and datamax also occurs.
At this time, the upper arm on signal is turned off once at point B, turned on again when the voltage datau and the counter match, finally turned off at point C, and the circuit shifts to a three-phase short circuit. Thus, even when the voltage of the capacitor is applied twice (the total time is the predetermined period T1), the characteristics are the same as when the pulse voltage is applied for the continuous period T1.

As described above, the voltage from the capacitor is changed to PW
The addition as the M signal is also effective in correcting the bias of the current at the start of the three-phase short circuit and preventing an excessive current.

The above-described processing has been described by taking as an example a case where a pulse voltage is applied to the U phase, but can also be applied to a case where a pulse voltage is applied to the V phase and the W phase. In other words, another feature of the present invention is that the control unit 11 performs on / off control using a PWM method,
The P / P is applied to the preceding on / off control executed by the short-circuit transfer means.
The point is that the WM system is also used and the configuration is simplified.

The above description is based on the assumption that 1
It is assumed that the largest transient current flows in one phase (for example, the U phase), and the optimal time point at which a pulse voltage is applied to the one phase is determined from, for example, the magnetic pole position. On the other hand, another method is conceivable. This will be described below. For example, by using the magnetic pole position detected by the magnetic pole position detecting means provided in the permanent magnet type synchronous motor, by providing "phase selecting means" for selecting a phase in which the largest transient current flows, the U, V, and W phases are provided. Because the three-phase short circuit can be started immediately for the selected phase,
There is an advantage that the three-phase short-circuit transition process can be started more reliably and in a shorter time than when waiting for the optimal phase (predetermined time) for only one phase.

The "cancellation control means" for controlling the selected phase by applying the electric charge accumulated in the smoothing capacitor for a predetermined period to cancel the transient current component as described above. With the provision, it is possible to prevent an overcurrent generated at the time of three-phase short circuit. It can be said that this method is suitable for an electric vehicle control device of an electric vehicle in which safety is regarded as important.

That is, another feature of the present invention is that in the control device for an electric vehicle, when the switching control (on / off control) of the rotating three-phase permanent magnet synchronous motor is suddenly stopped, the permanent magnet synchronous motor is stopped. Phase selecting means for selecting the phase of the switching element through which the transient current component generated by the generated power flows, and applying the stored power of the smoothing capacitor to the selected phase for a predetermined period to reduce the transient current component. And a cancellation control means for controlling the cancellation.

On the other hand, returning to FIG. 1, when the three-phase short circuit is performed, since the induced voltage of the motor 1 is not generated on the input side of the inverter 2, the auxiliary relay 8 and the main relay 7 are turned on. This is also effective because overcurrent does not flow through the resistor 9 and the connection circuit.

Further, the three-phase short circuit generates a braking torque in the permanent magnet type synchronous motor, and also has the effect of reducing the motor speed. Then, after the main relay 7 is turned on, if the current speed is within the range of the motor speed which can be controlled by the current control unit 12, the short-circuit transfer processing unit 13 is stopped, the current control unit 12 is restarted, and the voltage command obtained by the current control unit 12 is obtained. Is compared with the carrier and output as a PWM signal to the gate of the inverter.

Further, when the speed of the electric vehicle is too high on a sloping road (downhill) and the motor control (current control) is impossible, or when the electric vehicle is running at a high speed, a key switch is turned off to completely stop the control. The present invention relates to a control device for an electric vehicle (a control device for controlling a permanent magnet type synchronous motor used for traveling driving of an electric vehicle) in which a key switch is turned on again to start motor control from a state in which the vehicle is driven. The present invention is applicable, and is particularly effective in ensuring safety when the driver suddenly stops on / off control of the control device for an electric vehicle.

Further, by performing a three-phase short circuit of the permanent magnet type synchronous motor using the switching element of the inverter, the relay circuit can be turned on, and the speed of the electric vehicle can be reduced by the braking action. When the speed of the electric vehicle decreases, it is possible to stop the three-phase short circuit and start the control of the motor.

Further, this method can be applied to a case where a DC power supply such as a converter is used instead of a battery.

[0085]

According to the present invention, when the permanent magnet type synchronous motor rotates, the pre-control is executed, and then the three-phase short circuit is started, so that the generation of an excessive current is prevented. That is, the three-phase short-circuit processing at the time of restarting when the permanent magnet type synchronous motor is rotating at high speed can be performed without causing an excessive current to flow through the switching element at the beginning of the three-phase short-circuit. Thereby, the switching element can be prevented from being broken, which is effective in improving the safety of the control device for the permanent magnet type synchronous motor at the time of high speed rotation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a control device for a permanent magnet type synchronous motor according to an embodiment of the present invention.

FIG. 2 is a processing flowchart of short-circuit control in the embodiment of FIG. 1;

FIG. 3 is an operation explanatory diagram of a short-circuit control according to the embodiment of FIG. 1;

FIG. 4 is a diagram illustrating motor current-time characteristics during short-circuit control.

FIG. 5 is a diagram showing motor current and motor torque characteristics when three-phase short-circuiting is performed by executing advanced on / off control according to the embodiment of FIG. 1;

FIG. 6 is a diagram showing a motor equivalent circuit in the case of FIG. 5;

FIG. 7 is a diagram showing motor current-time characteristics in the case of FIG. 5;

FIG. 8 is a diagram showing a first timing of one embodiment according to the present invention.

FIG. 9 is a diagram illustrating a method of applying a capacitor voltage by comparing carriers according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating motor current and motor torque characteristics when a three-phase short circuit is performed by a conventional device.

FIG. 11 is a diagram illustrating a motor equivalent circuit in the case of FIG. 10;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Permanent magnet type synchronous motor, 2 ... Inverter, 3 ... Smoothing capacitor, 4 ... Magnetic pole position sensor, 5 ... Encoder,
6 current sensor, 7 main relay, 8 auxiliary relay,
9: resistance, 10: battery, 11: control unit, 12: current control unit, 13: short circuit transition processing unit, 14: voltage command switching unit, 15: carrier wave comparison unit, 16: PWM signal output permission unit, 17: capacitor Voltage application time calculation unit, 18 short-circuit voltage command calculation unit, 19 short-circuit signal output timing detection unit, 20, 21, 22, 23, 24, 25 switching device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sanshiro Ohara 2520 Oji Takaba, Hitachinaka City, Ibaraki Prefecture Inside the Automotive Equipment Division of Hitachi, Ltd.

Claims (10)

[Claims] An inverter for supplying AC power converted from DC power to a three-phase permanent magnet type synchronous motor through a switching element provided for each phase, and smoothing the DC power supplied to the inverter. A permanent magnet synchronous motor control device, comprising: a smoothing capacitor that performs on / off control of each of the switching elements to control the inverter; and wherein the control unit includes the permanent magnet synchronous motor. Before the control unit executes the on / off control of the three-phase short circuit at the time of rotation, the control unit performs a preceding on / off control of each of the switching elements, and thereafter, there is provided short circuit transition means for shifting to the three phase short circuit. For permanent magnet type synchronous motor. 2. The inverter according to claim 1, wherein the inverter forms a three-phase bridge circuit with at least six of the switching elements. A switching element for one phase or two phases connected to the positive side of the DC power supply and a switching element for another phase connected to the negative side of the DC power supply are turned on at a predetermined point in time determined by the state of the motor. A permanent magnet type synchronous motor control device, characterized in that after a predetermined period for suppressing a transient current has been continued, the on / off state of the switching element is switched to shift to a three-phase short circuit. 3. The three-phase short circuit according to claim 1, wherein said switching means switches on and off an electrical connection between said inverter and a DC power supply for supplying said DC power to said inverter. Opening / closing control means for turning on the opening / closing means after the completion of the control. 4. The control device for a permanent magnet type synchronous motor according to claim 1, wherein the control section performs the preceding on / off control performed by the short-circuit transfer section by a PWM method. . 5. The method according to claim 2, wherein the predetermined time is an inflection point at which the di / dt of the steady-state current component at the time of rotation changes from negative to positive or from positive to negative, or a time near the inflection point. Control device for a permanent magnet type synchronous motor. 6. The method according to claim 2, wherein the predetermined period is as follows:
A control device for a permanent magnet type synchronous motor, characterized in that the period is T1 determined from the relationship of the equation (5). T1 = −τ · ln (i2 / (i2 + i1)) (5) where τ is the decay time constant of the transient current component when the three-phase is short-circuited, i1 is the amplitude of the steady-state current component when the three-phase is short-circuited, and i2 is for smoothing The final value of the current flowing through the capacitor voltage, ln, is the natural logarithm. 7. The control device for a permanent magnet type synchronous motor according to claim 2, wherein the predetermined period is changed according to the magnitude of the voltage of the smoothing capacitor. 8. The control device for a permanent magnet synchronous motor according to claim 5, wherein the inflection point is determined from a magnetic pole position of the permanent magnet synchronous motor. 9. A permanent magnet synchronous motor control device for switching a rotating three-phase permanent magnet synchronous motor from a free-run state to a drive by an inverter, wherein the control device starts from a predetermined time point determined by a magnetic pole position of the permanent magnet synchronous motor. A control device for a permanent magnet type synchronous motor, wherein a switching control for canceling a transient current caused by a three-phase short circuit is performed by an inverter. 10. A permanent magnet type synchronous motor for driving an electric vehicle according to any one of claims 1 to 4 or 9.
A control device for an electric vehicle, wherein the control is performed using the control device for a permanent magnet type synchronous motor described in the above item.