JP3394436B2 - Control device for permanent magnet type synchronous motor and control device for electric vehicle - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[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 Laid-Open No. 6-315201. According to the disclosed technique, the control of the permanent magnet synchronous motor is started when the permanent magnet synchronous motor is rotating at a high speed, or the rotational speed of the permanent magnet synchronous motor is too high and exceeds the controllable range. For example, when the switching element of the inverter is off, 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 the relay circuit in order to start or restart the control of the permanent magnet synchronous motor as it is, the battery is overcharged. Therefore, a contactor that opens the connection between the inverter and the permanent magnet synchronous motor is provided, and the connection between the inverter and the permanent magnet synchronous motor is provided when the power supply to the pre-drive circuit that drives the switching of the inverter is cut off. Is opened to prevent the appearance of the high DC voltage on the input side of the inverter due to the power generation operation of the permanent magnet type synchronous motor.

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

Further, according to Japanese Patent Laid-Open No. 1-190286, among the six switching elements of the inverter, at least two of the three switching elements connected to the negative side of the DC power source are turned on at the same time. A technique is disclosed in which a braking force is generated in a permanent magnet motor by a short circuit to perform stop maintenance control.

Since the technique disclosed in Japanese Patent Laid-Open No. 1-190286 is a control at the time of stop and not at the time of traveling, it is a three-phase short circuit when the permanent magnet type synchronous motor is rotating at a high speed. However, the problem remains that a large current flows from the motor to the switching element of the inverter at the initial stage (transitionally), and the use of a switching element having a maximum allowable current has a drawback of increasing cost.

A case where a three-phase short circuit is required in a permanent magnet type synchronous motor control device which performs an on / off control operation will be described with reference to FIG. Figure 3
It is a figure explaining the motor current and motor torque characteristic at the time of performing a phase short circuit.

In controlling the three-phase short circuit, all switching elements 20, 22, 24 connected to the positive side of the DC power supply are turned on, and all switching elements 21, 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 switched to the switching element 2
Flowing through 0, 22, 24 and its associated diode, the three phase terminals of motor 1 will be physically coupled.

The three-phase short circuit causes the switching element 21,
23, 25 are turned on, switching elements 20, 22, 24
It will be achieved even if it is turned off.

However, when the three-phase short circuit is simply performed, the following problems occur. Without any contrivance, turn on the other switching element simultaneously at "time 0" and
The characteristics of the motor current and the motor torque when the phase short circuit is performed (the other switching element remains off) are shown. Fig. 10 (a) shows the U phase current, Fig. 10 (b) shows the V phase current, FIG. 10C shows the W-phase current, and FIG. 10D shows the torque characteristics.

The characteristics shown here are that the U-phase current first flows largely to the positive side, and the V-phase and W-phase currents flow to the negative side, and after a sufficient time has passed, the U-phase Both V phase and W phase settle to a sine wave centered on 0. At this time, the motor torque also experiences torque fluctuations that lead to vibrations. The characteristic that the motor current is 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 is biased, depending on the magnetic pole position of the permanent magnet at the start of the three-phase short circuit. , Because it is biased toward the negative side.

[0011]

In the prior art, 3
Fig. 1 shows the phenomenon that the motor current is biased at the beginning of phase short circuit.
Further description will be given with reference to FIG. FIG. 11 shows FIG.
It is a figure explaining a motor equivalent circuit in case of 0. Figure 4
FIG. 6 is a diagram illustrating a motor current-time characteristic when a three-phase short circuit is performed.

That is, FIG. 11 (a) 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. Figure 11 (a)
Current flowing in the equivalent circuit of (called a steady 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. A current (referred to as a transient current component) flowing through the equivalent circuit of FIG. 11B is shown in FIG. 4B. The current when the three-phase short circuit is performed can be expressed as the sum of the steady current component of FIG. 4A and the transient current component of FIG.

The steady-state current component of FIG. 4 (a) is the characteristic of the current for one phase (U phase) (sine wave of amplitude i1) when a sufficient time has elapsed after the start of the three-phase short circuit. Also, although not shown,
If the frequency of the electric current is very high, the induced voltage eu is generated in a phase advanced by about 90 ° with respect to the electric current. The bias of the current at the start of the three-phase short circuit changes depending on which phase of the steady current component the three-phase short circuit start timing is.

That is, in the steady current component of FIG.
When the three-phase short circuit is started at the timing of the phase of (1), the current starts to flow regardless of whether it is positive or negative. When a three-phase short circuit is started at the timing of the phase at the time of (2), the current starts to flow unevenly under the switching element connected to the negative side, and the three-phase is started at the timing of the phase at the time of (3). When the short circuit is started (corresponding to the case shown in FIG. 10A), the current begins to flow unevenly in the switching element connected to the positive electrode side.

This is because the current is 0 before starting the three-phase short circuit, and when the three-phase short circuit is started at the timing of the phase at time (2), the current starts to flow from 0 to the negative side.
After that, it flows up to twice the amplitude of the sine wave. As well
When the three-phase short circuit is started at the timing of the phase at the time of (3), the current starts to flow from 0 to the positive side, and then flows up to twice the amplitude of the sine wave. Therefore, if a three-phase short circuit is started at the timing that is the phase at time (1),
Unbiased for one phase (U phase), but V phase, W
Since the phases are 120 ° and 240 ° behind the U phase, 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) shows the bias of the current 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 is attenuated by the time constant τ expressed by the equation (1). τ = La / Ra (Equation 1) The three-phase short-circuit transient current components of V phase and W phase also decay with the time constant τ.

Further, the three-phase short circuit transient current component iu 'can be expressed by the 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 starts in the steady current component of Fig. 4 (a). The initial value iu'0 is -i1 when the sign is inverted, that is, when the three-phase short circuit is started at the timing of the phase of (2), and i1 is obtained in the case of (3). Similarly, the initial values of the V-phase and W-phase three-phase short-circuit transient current components are also the inversion of 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-state current components.

If the current flowing at the start of the three-phase short circuit exceeds the maximum current value of the switching element (IGBT, etc.), the switching element may be destroyed. Also, FIG. 10 (d)
The motor torque is fluctuating as shown in the torque characteristic of 1), which may adversely affect the drive system (gear, etc.).

An object of the present invention is to provide a controller for a permanent magnet type synchronous motor and a controller for an electric vehicle, which avoids the generation of excessive current and leads to cost reduction.

[0020]

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 controller for executing on / off control of each switching element including three-phase short circuit of the permanent magnet type synchronous motor and controlling the inverter. A magnet-type synchronous motor control device, wherein before the control unit executes the on-off control of the three-phase short circuit when the permanent magnet-type synchronous motor rotates, the control unit executes the preceding on-off control of each of the switching elements, and thereafter. And a short-circuit transfer means for transferring to the three-phase short circuit.

Another feature of the present invention is that the inverter constitutes a three-phase bridge circuit with at least six of the switching elements, and the short-circuit transition means includes: when all the switching elements are in an off state. One-phase or two-phase switching elements connected to the positive side of the DC power supply and switching elements of 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. The permanent magnet synchronous motor control device switches the switching element to the on-off state and shifts to a three-phase short circuit after the switching element is brought into a state and continued for a predetermined period to suppress the transient current.

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

Further, an electric vehicle control device that achieves the above object is controlled by using the permanent magnet type synchronous motor control device.

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 a rotating three-phase permanent magnet synchronous motor flows, and a phase selecting means for the selected phase. And a canceling control unit for controlling the canceling of the transient current component by applying the stored power of the smoothing capacitor for a predetermined period.

According to the present invention, since the pre-control is executed when the permanent magnet type synchronous motor is rotated and then the three-phase short circuit is performed, generation of an excessive current is prevented. That is, the three-phase short-circuit process 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 initial stage of the three-phase short-circuit. As a result, it is possible to prevent the switching element from being broken, and it is effective to enhance the safety of the permanent magnet type synchronous motor control device at high speed rotation.

[0026]

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

The control unit 11 includes a current control unit 12, a short circuit shift processing unit 13, a voltage command switching unit 14, and a carrier wave comparison unit 1.
5, the PWM signal output permission unit 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, the control method of 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 power supplied to the motor by controlling the on / off of the switching element of the inverter to control the speed and torque of the permanent magnet type synchronous motor will be described.

As a process before starting the switching control of the inverter 2, the control unit 11 first turns on the auxiliary relay 8 to charge the capacitor 3 from the battery 10. 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 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 is turned off.

The control unit 11 starts the current control unit 12 after the main relay 7 is turned on, 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. In the current controller 12, the voltage command is calculated by matching 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. The current command is calculated from the torque command, the motor speed, etc. by vector control or the like.

In the electric vehicle control device or the like, the torque command is obtained from the accelerator opening degree or the like. Calculate the motor speed control,
The torque command may be obtained. Further, the magnetic pole position required for current control is determined by the magnetic pole position sensor 4 serving as magnetic pole position detecting means.
Calculate based on the signal from. Motor speed (motor speed)
Is calculated from the pulse output from the encoder 5.

The voltage command switching unit 14 selects a voltage command obtained by current control and outputs it to the carrier wave comparing unit 15. The carrier wave comparison unit 15 compares the three-phase voltage command and the carrier wave, and creates PWM signals for each of the three phases. Here, the carrier wave comparison unit 15 may use a timer unit or the like with a built-in microcomputer. The PWM signal output permission unit 16 is a place where the PWM signal output to the gate unit of the inverter 2 is prohibited or permitted. If the PWM signal output 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 permission unit 16 may use the PWM signal output stop function built in the microcomputer provided in the control unit 11 (or the control device itself),
It may be configured by an external circuit that outputs a control signal for permitting output from the microcomputer and performs AND with the PWM signal.

When the number of rotations of the motor increases and exceeds the controllable range, the control unit 11 stops the current control unit 12 and prohibits the PWM signal output by the PWM signal output permission unit 16, Switching elements 20 and 2 of the inverter 2
Turn off all 1, 22, 23, 24, and 25. 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
Turns off the main relay 7 and executes control to 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 a three-phase short circuit) is executed so that the relays can be turned on again so that no induced voltage appears on the input side of. Then, while the three-phase short circuit is being performed, the auxiliary relay 8 is turned on and then the main relay 7 is turned on, and the braking operation of the three-phase short circuit causes the motor rotation speed to fall to the motor controllable region, and then the current control is performed. Part 12 is restarted.

In addition, the control processing of the three-phase short circuit is also required in the following cases. That is, while the motor 1 is rotating at high speed,
For example, when the control power source (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. When the operator of the control device (driver of the electric vehicle) turns on the control power and 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 (the circuit including only the main relay 7 or the circuit including the main relay 7 and the auxiliary relay 8) is burnt out and the battery is overcharged. Therefore, in order to improve the reliability, it is necessary to perform the control processing of the three-phase short circuit of the motor 1 before turning on the relay.

In controlling 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 source, and the negative side of the DC power source. Each of the connected switching elements 21, 23 and 25 outputs a signal for keeping it off,
Perform a three-phase short circuit. Alternatively, the switching elements 21, 23 and 25 are turned on at the same time, and the switching elements 20, 22 and 24 are output as a signal to remain off,
Perform a three-phase short circuit. By this control, all the currents of the three-phase terminals of the motor 1 flow through the switching elements 20, 22, 24 and the associated diodes, or through the switching elements 21, 23, 25 and the associated diodes. The three-phase terminals of the motor 1 Would be the same as physically connecting.

The feature of the control process according to the present invention is that the transient current component generated when a three-phase short circuit is simply performed without any measures at the start of the three-phase short circuit is stored in the smoothing capacitor 3 shown in FIG. Based on, the current is canceled by applying a current to the motor side.

Next, the short circuit control process according to the present invention will be described with reference to the flow chart of FIG. To perform this control process,
First, the smoothing capacitor 3 is calculated in the capacitor voltage application time calculator 17 of the short-circuit transfer processor 13 of the controller 11.
Is input (S201), and then the application time of the capacitor voltage (predetermined period T1 described later) is calculated (S201).
202). This is because the magnitude of the current passed through the motor 1 based on the stored power stored in the capacitor 3 is determined by the voltage of the capacitor 3 and the time for 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 application time (pulse width) of the required capacitor voltage after comparing with the carrier wave.
The voltage command is calculated so that

Here, it is assumed that the voltage command switching unit 14 selects the voltage command of the short circuit shift processing unit 13. next,
The short-circuit signal output timing detection unit 19 detects the "first timing" as the predetermined time point for the advanced on / off control (S204), and the PW of the advanced on / off control is performed.
A PWM signal output permission signal is output to the M signal output permission unit 16 (S205). Short circuit signal output timing detection unit 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 canceled and the transient current component is canceled in advance.
The M signal output permission signal is output. Then, after a lapse of a predetermined time T1, the control shifts to three-phase short circuit control (S20
6, S207).

The operation of this embodiment will be described with reference to FIG. 3 in the case where the largest transient current component flows in the U phase as shown in FIG. At the timing of time t0 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 passed,
As shown in (B), the U-phase switching element is switched on and off. 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-circuited state, FIG.
By configuring the above circuit for a predetermined time T1, it means that the pulse voltage VP U having the magnitude of the capacitor voltage Vc as shown in FIG. 6 and of the period T1 is applied to the U phase. Therefore, from the theorem 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 represented by the sum of the phase short circuit transient current components.
That is, it is the sum of the steady current component shown in FIG. 11, the three-phase short circuit transient current component, and the compensation current component shown in FIG. Therefore, by canceling the three-phase short circuit transient current component by the compensation current component, a large current is prevented from flowing.

As can be seen from FIG. 6, when the circuit constants of the respective phases are the same, the compensation currents of the V phase and the W phase flowing by the pulse voltage VPU have the same value. Therefore, in order to compensate the three-phase short-circuit transient current component in this embodiment, the V-phase and W-phase three-phase short-circuit transient currents are required to be equal.

Therefore, what is important in this series of operations is the time t0 at which the control is started and the method for determining the predetermined time T1. At time t0, the timing of the induced voltage that maximizes the absolute value of the steady current is set. Specifically, U in FIG.
It is time (3) when the steady-state current of the phase becomes maximum. At this time,
The steady-state currents of the V-phase and the W-phase are ½ of the U-phase current (however, the signs are opposite) and have the same value, so the above condition is satisfied. Details will be described with reference to FIG.

Since the three-phase short circuit transient current component differs depending on the phase at the time of starting the three-phase short circuit, the first timing for applying the pulse voltage is set as follows. FIG. 8 is a diagram showing a first timing according to an embodiment of the present invention. FIG. 8 shows the U-phase, V-phase, and W-phase steady-state current components and the U-phase induced voltage components. The steady current components (iu, iv, iw) have the same amplitude i1 and a phase of 120 °.
It is deviating from each other. The induced voltage (only eu is shown) is generated when the magnetic flux of the permanent magnet that links the stator windings of the permanent magnet type synchronous motor changes, and the phase of the induced voltage is, for example, the permanent magnet type synchronous motor. Can be obtained from the magnetic pole position detected by the existing magnetic pole position detection means.
Since the motor current is assumed to be in a high frequency region here, the phase difference between the induced voltage and the current is approximately 90 °.

In the phase at the time point indicated by the dotted line drawn vertically in the drawing of FIG. 8, the V-phase current and the W-phase current are equal in amplitude (i 1/2), and further the amplitude of the U-phase current (-i 1) However, the magnitude is halved. If a normal three-phase short circuit is started at this phase, 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”. It becomes 1/2 ".

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

Iu "=-i2 {1-exp (-t / τ)} (Equation 3) i2 = 2Vc / (3Ra) (Equation 4) However, the time constant τ can be expressed by La / Ra. The V-phase compensation current component iv "and the W-phase compensation current component iw" are 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 coincide. ) Is used to determine the predetermined time T1. When the time constant τ is large, it can be determined by linear approximation.One example of a specific method for determining the predetermined time T1 will be described below.

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

Further, the switching elements 21, 22, 24
The first timing when both are turned on at the same time is an inflection point where di / dt shifts 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, during the predetermined period T1 for applying the pulse voltage by the capacitor, the three-phase short circuit transient current component iu '(initial value i1) shown in FIG. 4 (b) and the current by the pulse voltage shown in FIG.
It is the time when the sum with iu '' becomes zero (0). Therefore, when this time is solved by an 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 processing time to calculate the predetermined period T1 by, for example, a microcomputer, it is desirable to prepare a table in which the predetermined period T1 is calculated according to the capacitor voltage in advance and use it. That is, another feature of the present invention is that the predetermined period T1 is changed depending on the magnitude of the voltage of the smoothing capacitor. In other words, the means for detecting the voltage of the smoothing capacitor and calculating the predetermined period T1 is provided.

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

Further, although the first timing is set accurately in this embodiment, for the motor rotating at high speed,
It can be said that it is difficult for the sampling process of the microcomputer to accurately detect the phase at the time point shown in FIG. Therefore, the predetermined period T1 to which the pulse voltage is applied has a certain width, and therefore, as the first timing, a predetermined period T1 is provided before and after the phase at the time point shown in FIG. In other words, even if a time point within the range of the predetermined area set before and after the inflection point (for example, the area having the same time width T1 as the predetermined period T1 before and after the inflection point) is adopted, the same result is obtained. The effect of can be obtained. Furthermore, the predetermined period T1
Even if it is a predetermined area that has a time width (2T1) that is about twice the
It has been confirmed that it has the effect of not breaking the IGBT. Incidentally, the time width of this embodiment is T1 = 150 (μsec)
It is a degree.

As shown in FIG. 3, when the switching elements are switched at the predetermined time T1 calculated from the capacitor voltage Vc, etc., the pulse voltage VPU is passed after the predetermined time T1 has elapsed.
Becomes 0. Therefore, the compensation current components iu ", i of each phase
v "and iw" gradually decrease to 0 with a time constant τ as shown in FIG. If 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 the same after the elapse of the predetermined time T1, the waveform after the elapse of the predetermined period T1 of FIG. Although the sign is different from that of the three-phase short circuit transient current component of b), it has the same waveform, that is, the U-phase compensation current component iu ″ and the three-phase short-circuit transient current component iu ′ flowing in the U phase when a predetermined time T1 has elapsed.
Since the predetermined time T1 is determined so that the absolute values of the two coincide with each other, 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.

On the contrary, the other switching element 21,
A case may be considered in which one of the switching elements 22 and 24 is turned on at the same time. In this case, the first timing of turning on
The (phase) is shifted by 180 ° from the case where the switching elements 20, 23 and 25 are turned on.

Then, after a predetermined period of time, one of the switching elements 22 and 24 is turned off and the other of the switching elements 23 and 25 is 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 through the motor 1 to the switching element 21.
Flow to.

Furthermore, the switching elements 20, 2
A method of short-circuiting three phases by one of the switching elements 20, 22, and 24 after simultaneously turning on the switching elements 3 and 25 or simultaneously turning on the switching elements 21, 22 and 24 is also conceivable.

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

As described above, ON / OFF of the switching element can be arbitrarily selected in relation to the induced voltage.
Therefore, when restarting the motor control by the inverter from the state where the motor 1 is rotating in free run, in products that require the time to restart as short as possible, the state of the induced voltage should be 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 switching methods according to the above.

In the case of a product in which there is no problem even if it takes about 10 ms to 100 ms to restart the motor control, 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 becomes maximum from the induced voltage of the phase and set the time as t0 to start the control.

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

The control device of the present invention executes the preceding on / off control of each switching element to avoid the excessive current generated at the initial stage when the three-phase short circuit is performed during the rotation of the motor 1, and the three-phase short circuit is performed. Short-circuit transfer means to be transferred (that is, the constituent means of the short-circuit transfer processing unit 13 or the short-circuit transfer processing unit 1
3, voltage command switching unit 14, carrier wave comparing unit 15 and P
The WM signal output permission unit 16 and the like) are provided. According to the present invention, it is possible to introduce a 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, which leads to cost reduction and reliability improvement. The effect is obtained.

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

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

FIG. 9 is a diagram showing a method of applying a capacitor voltage by carrier wave comparison according to an embodiment of the present invention.
That is, there is shown an embodiment of the short-circuiting transition means for outputting a pulse voltage while also having a function of outputting a PWM signal by a counter incorporated in a microcomputer. The short-circuit shifting means of this embodiment includes a short-circuit shifting processing unit 13, a voltage command switching unit 14, a carrier wave comparing unit 15, and a PWM signal output permission unit 16. This will be described below.

In FIG. 9, the clock is counted to 0.
There are two counters that repeat up and down between the data and datamax, and the U phase V phase W phase voltage values datau, datav, dataw
, Which can automatically output 6 PWM signals for driving U-phase, V-phase, and W-phase switching elements by setting the value in the dedicated register and comparing the values of the counter and the register. Is. By comparing with two counters, the short circuit prevention time of the upper and lower switching elements is created. When performing the current control, the voltage value obtained by calculating the current control is set in the 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. 9 (a), the voltage command datau is set to zero (0) before the output of the PWM signal is permitted. Then, the signal of the upper arm is turned on and the signal of the lower arm is turned off. When the PWM signal output is permitted, the signal of the upper arm operates ON / OFF of the switching element 20 of FIG. 1, and the signal of the lower arm operates ON / OFF of the switching element 21 of FIG.

For the V phase and the W phase, as shown in FIG. 9 (b), the voltage commands datav and d before the PWM signal output is permitted.
With ataw set to the value of datamax, the upper arm signal is off and the lower arm signal is on. When the PWM signal output permission is given to the signal of the upper arm, the switching elements 22 and 24 of FIG. 1 are turned on and off, and the signal of the lower arm is turned on and off of the switching elements 23 and 25 of FIG.

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

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

In this way, 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 the excessive current.

The above-described processing has been described by taking the case where the pulse voltage is applied to the U phase as an example, but it can be applied to the case where the 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 executes the on / off control by using the PWM method, and the short-circuit transition means includes:
The preceding ON / OFF control executed by the short-circuit transfer means is set to the P
The point is that the WM method is also used and the configuration is simplified.

By the way, in the above description, when the three-phase short circuit occurs,
It is assumed that the largest transient current flows in one phase (for example, U phase), and the optimum time to apply the pulse voltage for the one phase is determined from the magnetic pole position, for example. On the other hand, another method can be considered. This will be described below. For example, by providing "phase selection means" for selecting the phase through which the largest transient current flows, by using the magnetic pole position detected by the magnetic pole position detection means included in the permanent magnet type synchronous motor, the U, V, W phases are provided. Since a 3-phase short circuit can be started immediately for the selected phase of
There is an advantage that the three-phase short-circuit transfer process can be started more reliably and in a shorter time than waiting for the optimum phase (predetermined time point) for only one phase.

Then, as described above, the "cancellation control means" for controlling so as to cancel the transient current component by applying the electric charge accumulated in the smoothing capacitor to the selected phase for a predetermined period as described above. By providing the overcurrent, it is possible to prevent an overcurrent generated when a three-phase short circuit occurs. It can be said that this method is suitable for an electric vehicle control device of an electric vehicle where safety is important.

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

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

The three-phase short circuit also has an effect of generating a brake torque in the permanent magnet type synchronous motor and reducing the motor speed. Then, after the main relay 7 is turned on, if it is within the range of the motor speed that the current control unit 12 can perform, the short circuit transition processing unit 13 is stopped and the current control unit 12 is restarted, and the voltage command obtained as a result of the current control unit 12 Is compared with the carrier wave and output as a PWM signal to the gate section of the inverter.

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

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.

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

[0085]

According to the present invention, since the three-phase short circuit is performed after the pre-control is executed during the rotation of the permanent magnet type synchronous motor, the generation of the excessive current is prevented. That is, the three-phase short-circuit process 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 initial stage of the three-phase short-circuit. As a result, it is possible to prevent the switching element from being broken, and it is effective to enhance the safety of the permanent magnet type synchronous motor control device at high speed rotation.

[Brief description of drawings]

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

FIG. 2 is a process flow chart of short circuit control in the embodiment of FIG.

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

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 a three-phase short circuit is performed by executing the preceding 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 a motor current-time characteristic in the case of FIG.

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

FIG. 9 is a diagram showing 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.

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

[Explanation 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 part, 12 ... Current control part, 13 ... Short circuit transition processing part, 14 ... Voltage command switching part, 15 ... Carrier comparison part, 16 ... PWM signal output permission part, 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 element

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Sanshiro Ohara 2520 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi Ltd. Automotive Equipment Division (56) Reference JP-A-5-268794 (JP, A) JP-A 7-184394 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 6/24 B60L 9/18

Claims (9)

(57) [Claims] 1. A three-phase bridge circuit comprising at least six switching elements, wherein an AC power converted from DC power via the switching elements is supplied to a three-phase permanent magnet synchronous motor and an inverter is supplied to the inverter. A smoothing capacitor for smoothing the DC power,
In a motor control device including a control unit that controls the inverter, the control unit controls the restart of the three-phase permanent magnet synchronous motor while the switching elements are all in the OFF state. Prior to the phase short-circuit control, one phase or two phases of switching elements connected to the positive side of the DC power of the three-phase bridge circuit and the negative side of the DC power supply are connected to correspond to the positive side. The switching element for two phases or one phase as the other phase is turned on at a predetermined time determined by the magnetic pole position of the motor to apply the capacitor voltage so as to cancel the transient current component and suppress the transient current component. In order to keep the voltage applied for a predetermined period of time, the switching element is controlled for 3 times.
A control unit for a permanent magnet type synchronous motor, which is a control unit having a short-circuit shifting means for switching to phase short-circuit control. 2. The opening / closing means for turning on / off an electrical connection between the inverter and a DC power supply for supplying the DC power to the inverter, and the three-phase short-circuit transfer control by the short-circuit transfer means. A control device for a permanent magnet type synchronous motor, wherein the control unit controls the opening / closing of closing the opening / closing means after completion. 3. The control device for a permanent magnet type synchronous motor according to claim 1, wherein the control of the switching element prior to the short-circuit control by the short-circuit shifting means is controlled by the control unit by a PWM method. . 4. The method of claim 1, wherein the predetermined time is the synchronous motor is shifted to the negative from the change of the maximum value or the minimum value or the constant current component of the constant current component during rotation negative from positive or positive A permanent magnet type synchronous motor controller characterized by being an inflection part. 5. The method of claim 1, wherein the predetermined time period, a permanent magnet synchronous motor control device, characterized in that the period T1 determined from the following relationship. T1 = -τ ・ ln (i2 / (i2 + i1)) where τ is the decay time constant of the transient current component at the time of three-phase short circuit, i1 is the amplitude of the steady current component at the time of three-phase short circuit, and i2 is the smoothing capacitor voltage. The final value of the current that flows, ln, is the natural logarithm. 6. The method of claim 1, wherein the predetermined time period, a permanent magnet synchronous motor control device, characterized in that vary based on the voltage of the smoothing capacitor. 7. The permanent magnet synchronous motor control device according to claim 4, wherein the inflection portion is determined from a magnetic pole position of the permanent magnet synchronous motor. 8. A permanent magnet synchronous motor control device for switching from a free-run rotation state of a three-phase permanent magnet synchronous motor to driving by an inverter, wherein the three-phase short circuit control by the inverter drive precedes the permanent magnet synchronous. A control unit including a short-circuit shift processing unit that shifts to 3-phase short-circuit control after performing switching control for canceling a transient current due to 3-phase short-circuit by the inverter from a predetermined time determined by the magnetic pole position of the motor. A controller for a permanent magnet type synchronous motor that features. 9. A permanent magnet type synchronous motor for driving an electric vehicle is controlled by using the permanent magnet type synchronous motor control device according to any one of claims 1 to 4 or 8. Control device for electric vehicle.