JPS607915B2 - Chiyotsupa control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on "a DC motor connected to multiple sections of dynamic braking resistor, a chopper connected in parallel to one section, and a contactor connected in parallel to the other section. This invention relates to an improvement of a chopper control device that continuously controls dynamic braking of a DC motor by combining control and contactor closing control.

Recently, the application of choppers to electric vehicles has become widespread, and an example of this is the application to control of dynamic braking of electric vehicles.

Conventionally, dynamic braking for electric cars involves connecting multiple resistors in series to the main motor, connecting a chopper in parallel to one of the multiple resistors, and connecting a contactor in parallel to the other resistor. The combination of a chopper and a contactor continuously reduced the resistance and controlled the braking force continuously.

FIG. 1 is an example of such dynamic braking control.

In Figure 1, M is the main motor and the smoothing reactor DCL
and braking resistors R, ~R4, and Ro are connected in series, and ~C4 is connected in parallel to the braking resistors R, ~R4, and a cam contactor,
A chopper CH is connected in parallel to the braking resistor O to constitute a dynamic braking circuit. The chopper shown in Fig. 1 is a series arc-extinguishing type repulsion pulse type chopper configured using reverse conduction type thyristors, and the main thyristor MTh and auxiliary thyristor ATh are turned off when the current command IP is not given. It is assumed that the commutating capacitor Co is charged with a voltage having the polarity shown in FIG.

First, when the on-gate signal ○nG is applied to the main thyristor MTh, the main thyristor MTh is turned on. Next, when the off-gate signal ○, which is output at a constant cycle, is applied to the auxiliary thyristor ATh and the main thyristor MTh, the auxiliary thyristor ATh turns on, so that the charging voltage of the commutating capacitor Co changes to the voltage between the commutating capacitor Co and commutating reactor Lo. is discharged in the closed circuit of the main thyristor MTh and the auxiliary thyristor Am,
The oscillating current at this time turns off the main thyristor MTh. That is, commutation occurs. Then, the commutation capacitor Co is charged with a voltage for the next commutation, and the commutation operation ends.

After this off-gate signal G is applied, the main thyristor Mm is turned off, and the commutating capacitor C is turned off. The period until the voltage for the next commutation is charged is the commutation period. In FIG. 1, the dynamic braking circuit is not configured in a state where the gate start signal GS and the current command IP are not given to the control device CE, and the chopper C
Since the on-gate signal ○nG and the off-gate signal 0 are not given to H, it is assumed that the chopper CH is in a narrowed state and the cam touch devices C, to C4 are in an open state.

Now, when the gate start signal GS is applied, a dynamic braking circuit is configured. At the same time, the off-gate signal ◯ is applied to the auxiliary thyristor ATh at a constant period from the control device CE, so that the auxiliary thyristor ATh is turned on.

This off-gate signal 0fG is also applied to the main thyristor MTh as an on-gate signal ○nG via the OR gate OR, so the main thyristor MTh turns on and the chopper CH
is the minimum conductivity state.

At this time, since the dynamic braking circuit is configured, the main motor voltage is generated according to the speed of the main motor M, the braking current IB flows in the direction shown in FIG. 1, and the speed of the main motor M begins to decrease. This braking current IB is detected by a DC current transformer DCCT, and is applied to the control device CE differentially from the current command IP.

On the other hand, since the current command IP is given to the control device CE at the same time as the gate start signal GS, a comparison is made with the braking current IB, and according to the deviation, an on-gate signal ○nG is applied to the main thyristor MTh, and the chopper CH is The conductivity rate increases.

As a result, the braking resistor Ro connected in parallel
The value of is gradually decreased, and the braking current IB is controlled in accordance with the current command IP. Eventually, when the current conductivity reaches the maximum, the camshaft controller advances to C, the cam contactor is turned on, the braking resistor R is short-circuited, and the braking current 18, is detected by the saturable reactor SCT.

The output signal of this saturable reactor SCT is the chopper CH
Since it is temporally unrelated to the operation of AND gate A
In addition to the memory circuit Me through G, the commutation period of the chopper CH is stored in the memory circuit Me with a negative signal of the reference pulse signal BP of equal width, that is, it is synchronized, and the output signal locks the control device CE. Narrow down the on-gate signal to 0 mG and the off-gate signal to 0.

As a result, the signal for locking the control device CE is not continuously applied during the commutation period of C.C., so it is possible to prevent commutation failure due to insufficient commutation exposure pressure of the commutation capacitor Co.

When the output of the saturable reactor SCT disappears, the reference pulse signal BP is sent to the memory circuit Me via the NAND gate NA.
, the memory circuit Me is reset, the control device CE is unlocked, and the chopper CH is controlled again by the same operation as described above.

Eventually, when the current conductivity reaches its maximum, 2 is applied to the cam contactor, the braking resistor R2 is short-circuited, and the braking current IB2 increases in the opposite direction to the saturable reactor S.
Since it is added to CT, the saturable reactor SCT operates, and the memory circuit Me operates, after which the same operation as described above is repeated.

While repeating the above operations, set the braking current IB to the current command IP.
control along.

As described above, in the conventional example, the output signal of the saturable reactor SCT, which is outputted temporally independent of the operation of the chopper CH, is stored in the storage circuit Me using the reference pulse signal BP, and the output signal is used to control the control device CE. operation is locked.

However, this memory circuit Me has a drawback in that it is susceptible to malfunctions due to the influence of noise and power supply fluctuations.

Therefore, if the memory circuit Me malfunctions due to noise or the like during switching between the chopper CH and the cam contactor, and its output becomes zero, the control device CE is unlocked, and the control device CE
The on-gate signal ○nG is output from the motor, causing the engine to operate, causing an overcurrent to flow and an excessive braking force to be applied, which may cause the vehicle to run with the wheels stopped rotating, causing what is known as a skid. Ta.

Furthermore, if the memory circuit Me malfunctions and an output signal is generated while controlling the Chotsupa CH, the control device CE is locked and the Chotsupa CH is narrowed down, resulting in a drop in the braking current 18 and the braking force. This causes problems such as increased braking distance.

Furthermore, if the memory circuit Me malfunctions during the commutation period, the gate signal will be applied continuously for a short period of time, so the commutation capacitor Co will not be sufficiently charged with the commutation voltage. It becomes impossible to turn off the chopper CH, and there is a possibility that commutation may fail or the element may be destroyed.

An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a chopper control device that can safely and reliably minimize the chopper conduction rate without causing chopper commutation failure or element destruction. .

The present invention includes means for generating a conductivity narrowing command signal when a contactor is turned on to short-circuit a dynamic braking resistor, and a reference pulse signal that has a pulse width equivalent to the commutation period of the chopper and is repeated at the operating frequency of the chopper. and an exclusive logic zero gate into which the conduction rate narrowing command signal and the reference pulse signal are input, and the chopper conductivity control means synchronizes with the rising edge of the output signal of the exclusive OR gate. The present invention is characterized in that it is configured to generate an off-gate signal to the chopper, and to inhibit output of a phase-controlled on-gate signal to the chopper while the output signal of the exclusive OR gate is present. FIG. 2 shows an embodiment of the present invention, and FIG. 3 is a diagram showing a time chart of the operation shown in FIG. First, gate start signal GS
In the state in which the control device CE is not given, the phase signal PS and the off-gate signal ○fG are narrowed down because the control device CE is locked, and therefore the chopper CH is also in a narrowed down state.

However, the control device CE always outputs a reference pulse signal BP having a width equal to the commutation period of the chopper CH at a constant cycle.

This reference pulse signal BP is A of the pulse width comparison circuit PWC.
It is input to the ND gate AG, but since the gate start signal GS is not given, AG is in a narrowed down state, and since AG2 is also narrowed down, the pulse width comparison circuit PWC is also in a locked state. be.

Here, when the gate start signal GS is applied to the control device CE and the pulse width comparison circuit PWC at the timing shown in FIG. 3, the respective locks are released.

Therefore, first, the reference pulse signal BP is applied to the AND gate AG.
, and is applied to the control device CE via the exclusive OR gate EOR, and is converted into an off-gate signal G in the control device CE, turning on the auxiliary thyristor ATh.

In this way, the control device CE does not directly create the off-gate signal 0 from the reference pulse signal BP, but once converts the reference pulse signal BP to the pulse width comparison circuit PWC (which is basically composed of an exclusive OR gate). ), and the off-gate signal ■G is generated from the output obtained.

The reason for this will be explained later. Also, the off-gate signal 0 is OR
Since the on-gate signal 〇nG is applied to the main thyristor MTh via the gate OR, the main thyristor MTh is turned on, and the chopper CH enters the minimum conduction rate state.

Thereafter, the braking current IB is controlled in accordance with the current command IP, but since this operation is the same as the conventional example, it will be omitted. Switching between C and C4 will be explained. When the flow rate of the chopper CH reaches the maximum, the control device CE detects this and applies it to the camshaft controller CC, which advances the camshaft controller CC and turns on the cam contactor C.
The braking resistor R, is short-circuited.

At this time, the braking current 18 flows in the direction of the arrow in FIG. 2 and is detected by the saturable reactor SCT. The output signal of this saturable reactor SCT is the pulse width comparison circuit PW.
Exclusive OR gate E
Added to OR.

This exclusive OR gate EOR obtains an output signal when signals of different levels are input, and the output becomes zero when signals of the same level are input.

Therefore, the pulse width comparison between the reference pulse signal BP via the AND gate A○ and the output signal of the saturable reactor SCT via the AND gate AG2 is performed by the exclusive OR gate EOR, and the output signal is It is applied to the control device CE as an output signal of the width comparison circuit PWC.

Then, in the control device ℃E, the pulse width comparison circuit PWC
The rising edge of the output signal is converted into a pulse and becomes the off-gate signal G, and is output to the chopper CH as the on-gate signal 0nG via the OR gate CR, so the chopper CH has the minimum distant current rate. In other words, when the maximum conductivity of the chopper is detected and one of the contactors C, ~C4 is inserted, and either of the dynamic braking resistors R, ~R4 is short-circuited, the conductivity of the chopper is immediately adjusted. If the motor is not heated, the motor current will increase rapidly.

Therefore, if the chopper is conductive (ON) when the output of the saturable reactor SCT occurs, it is immediately turned OFF.
F. For this purpose, the occurrence of the output of the saturable reactor SCT is detected as the output of the pulse width comparison circuit PWC, and is converted into an off-gate signal 0 by the control device CE.
The off-gate signal G is ~ Since the on-gate signal 0nG is also generated through the OR gate ORI, the previous off-gate signal ○ is generated and the chopper is at the end of commutation.The period when the commutation capacitor Co is not sufficiently charged (commutation period) must not be allowed to occur. For this reason, the function of setting a prohibition period by the reference pulse signal (with a width equivalent to the commutation period) and the on-gate signal ○n during the entire period when there is no reference pulse signal
It can be said that the pulse width comparison circuit PWC is responsible for the function of preventing G from occurring in the control device CE (the function of narrowing down the conduction rate to the minimum conduction rate). For this reason, as mentioned above, the control device CE
is the off-gate signal directly from the signal BP to the reference pulse.
Instead of creating a circle, a pulse width comparison circuit PWC is provided.

After that, while the output of the saturable reactor SCT continues, the EOR output (PWC output) shown in Fig. 3 will be "1" for the entire period except only the commutation period (BP generation period), and the off-gate will be turned off at the rising edge. In addition to the signal ○ being given periodically,
Generation of phase-controlled on-gate signal ○ medium G is prohibited.

In this way, the phase signal PS of E is narrowed down by the control device by the output signal of the saturable reactor SCT, so that the chopper CH is maintained at the minimum conductivity state while the saturable reactor SCT is operating.

Then, when the output signal of the saturable reactor SCT disappears, the output signal of the pulse width comparison circuit PWC becomes synchronized with the reference pulse signal BP and is applied to the control device CE. It is output in synchronization with the rising edge. In addition, saturable reactor S
When the output signal of CT disappears, the phase signal PS starts to be output, and the conduction rate of the chopper CH is controlled.

Eventually, when the current conduction rate reaches the maximum, 2 is applied to the cam contactor, the braking resistor R2 is short-circuited, and the braking current 182 flows in the direction shown in FIG.

This braking current IB2 is applied to the saturable reactor SCT in the opposite direction to IB, so the saturable reactor SCT
Thereafter, the pulse width comparison circuit PWC operates in the same manner as described above, and the conduction rate of the chopper CH becomes minimum.

By repeating the above operation, the braking current IB is changed to the current command I.
control along P.

Next, when the gate start signal GS is turned off, E and the pulse width comparison circuit PWC are locked in the control device, and finally only one on-gate signal ○nG and one off-gate signal ○red are given to the chopper CH. , the chopper CH enters the minimum conduction rate state, and since the phase signal PS is no longer output from the control device CE, the chopper CH stops here.

As described above, in this example, a pulse width comparison circuit is used,
Subtract the pulse width of the reference pulse signal, which is equal to the commutation period of the chopper, from the pulse width of the output signal of the saturable reactor,
The output signal is converted into a pulse in the control device to become an off-gate signal, and is then given to the chopper as an on-gate signal via an OR gate to minimize the conduction rate, so it is possible to determine at what timing the saturable reactor Even in operation, continuous gate signals are not applied during the commutation period of the chopper, which has the advantage of preventing chopper commutation failure and element destruction.

Furthermore, since the circuit for comparing pulse widths does not use a memory element that is susceptible to noise and power supply voltage fluctuations, the pulse width comparison circuit does not malfunction due to noise or power supply voltage fluctuations.

Therefore, there is an advantage that the braking current does not become overcurrent or drop.

Furthermore, since the chopper is not stopped by the output signal of the saturable reactor but is set to the minimum conduction rate, there is an advantage that a drop in the braking current during this period can be prevented, albeit slightly.

FIG. 4 shows another embodiment of the present invention, in which a one-shot circuit that can be operated by a gate start signal is used to obtain a pulse signal of a constant width when the output signal of a saturable reactor is applied. At the same time, obtain a negation signal of the output of the saturable reactor, first lock the control device with the negation signal of the output of the saturable reactor, narrow down only the on-gate signal of the chopper, and subtract the reference signal from the pulse signal of a constant width. This pulse signal is obtained and added to the chopper as an off-gate signal for the chopper, thereby minimizing the current flow rate of the chopper.

First, when the gate start signal GS is not applied, the transistor Tr of the one-shot circuit OS is off, and its collector voltage VcE is applied to the base of the transistor Tr2 via the resistor R8.

Therefore, Tr2 is turned on, but its saturation voltage is extremely small, so if this is ignored, the collector voltage of Tr2 is V
cE2 becomes zero.

Further, since the collector voltage Vc82 of the transistor Tr2 is zero, the control device CE is locked, and the phase control signal PSS is also in a narrowed state.

Furthermore, since the collector voltage VcE of the transistor Tr is applied to the base of the transistor Tr3 via the resistor R,o, Tr3 is in the on state, and the collector voltage VcE is applied to the base of the transistor Tr3 through the resistor R,o.
E3 is zero.

Therefore, the reference pulse signal BP having a width equal to the commutation period of the chopper CH is bypassed by the transistor Tr3 and is not applied to the off-pulse conversion circuit fPT.

In addition, the collector voltage VcE of the transistor Tr is also applied to the collector of the transistor Tr4 via the resistor R4, and the gate start signal GS whose phase is inverted by the delay circuit TD is connected to the base of the transistor Tr4. Since the reference pulse signal BP is also applied through the circuit R, 3, Tr4 is in the on state. Therefore, if the gate start signal GS is not given, the control device CE is narrowed down, so the phase control signal PSS is not applied to the on-pulse conversion circuit ○nPT, and the reference pulse signal BP
is also not added to the PT of the off-pulse conversion circuit. here,
When a gate start signal GS as shown in FIG. 6 is applied to the one-shot circuit OS, a base current flows to the transistor Tr through the resistor R5, so Tr is turned on and the transistor Tr is turned on.
2 turns off.

Therefore, the collector voltage VcB of the transistor Tr,
becomes zero, and the collector voltage VcE4 of Tr4 also becomes zero.

Further, the transistor Tr3 is also turned off. transistor T
When these are turned off, a voltage VcE2 is generated at the collector thereof, and the control device CE is now unlocked. At the same time, resistor R9 and capacitor C are connected to DC power source Ed.

A base current flows through the transistor Tr through the transistor Tr and the resistor R7, positive feedback acts on the transistor Tr, and a voltage is charged to the capacitor Cos. On the other hand, the gate start signal GS is also applied to the delay circuit TD.

This delay circuit TD has a phase inversion function, and when no signal is input, a voltage is generated at the output terminal.

When a signal is applied, the output becomes zero in synchronization with the signal, and when the signal is cut off, a voltage is generated at the output terminal after a certain period of time.

Therefore, when the gate start signal GS is applied, the output voltage of the delay circuit TD becomes zero, and accordingly, the transistor Tr4 is turned off.

At this time, since the transistor Tr3 is off, the reference pulse BP output from the control device °C is connected to the resistor R,
．． and off-pulse conversion circuit ■ via diode Dd2.
Added to PT, pulse converted and off gate signal ○
Since the auxiliary thyristor ATh is added to the auxiliary thyristor ATh, the auxiliary thyristor ATh is turned on. Also, since the off-gate signal 0 is applied to the main thyristor MTh as the on-gate signal ○nC via the OR gate OR, the main thyristor MT
h is turned on, and the chopper CH enters the minimum conduction rate state.

Thereafter, the braking current IB is controlled in accordance with the current command IP, but since this operation is the same as in the conventional example, it will be omitted.
Switching between H and cam contactors C and C4 will be explained.
When the flow rate of the chopper CH reaches the maximum, the control device CE detects this and applies it to the camshaft controller CC, which advances the camshaft controller CC and turns on the cam contactor C. The braking resistor R, is short-circuited.

At this time, the braking current IB flows in the direction of the arrow in FIG. 4 and is detected by the saturable reactor SCT. The output signal of this saturable reactor SCT is the one-shot circuit OS
Since it is applied to the base of the transistor Tr2 through the resistor R, 5, Tr2 is turned on, the control device CE is locked, and the phase control signal PSS is narrowed down. Furthermore, when the transistor Tr2 is turned on, the voltage charged in the capacitor Cos is transferred from the transistor Tr2 to the diode Dd.
, → is discharged in the closed circuit of resistor R7.

At this time, the forward voltage drop generated across the diode Dd is applied as a reverse voltage between the emitter and base of the transistor Tr, so that the transistor Tr is connected to the capacitor C.
It is turned off for a time approximately determined by os and the discharge time constant of resistor R7.

The collector voltage of this transistor Tr becomes the output signal of the one-shot circuit OS.

Then, the output signal of the one-shot circuit OS is connected to the resistor R,
The reference pulse signal BP is applied to the base of the transistor Tr3 through the transistor Tr3, so that Tr3 is turned on and the reference pulse signal BP is bypassed.

Moreover, the output signal of the one-shot circuit OS is connected to the resistor R, 4
However, when the timing overlaps with the reference pulse signal BP, which is applied to the base of Tr4 via resistor R,2, T
The collector voltage VcE4 of r4 is as shown in FIG.

That is, the reference pulse signal BP is subtracted from the output signal of the one-shot circuit OS, and this remaining pulse signal is sent to the off-pulse conversion circuit P via the diode DQ.
fPn is added, and the rising portion is converted into a pulse.

Therefore, as shown in FIG.
An off-gate signal mG synchronized with the rise of collector voltage Vc84 of r4 is obtained.

Since this off-gate signal 0fC is outputted to the chopper CH as an on-gate signal 0nG via the OR gate OR, its flow rate is minimized.

Eventually, when the charging voltage of the capacitor Cos is discharged, the forward voltage drop of the diode Dd decreases, and the reverse voltage effect on the transistor Tr disappears, so that the transistor Tr is turned on again.

That is, since the output signal of the one-shot circuit OS disappears, the transistor Tr3 is turned off and the transistor Tr4 is turned on.

As a result, the reference pulse signal BP is again applied to the resistors R, . is added to the PT of the off-pulse conversion circuit via the diode Dd2, and is converted into a pulse to become the off-gate signal 0fG, which is then passed through the OR gate OR to the on-gate signal ○nG.
is added to the chopper, so the minimum conductivity state continues. Then, when the output of the saturable reactor SCT becomes zero, the transistor Tr2 is turned off, so that the output of the control device CE becomes zero.
The lock is released, the phase control signal tower S is added to the on-pulse conversion circuit omPT, and thereafter the chopper CH is controlled again by the same operation as described above.

On the other hand, since transistor Tr2 is turned off, capacitor C
Voltage begins to be charged to the OS.

Then, when the current conductivity reaches the maximum, the cam contactor is injected with a current of 2, the braking resistor R2 is short-circuited, and the braking current IB2 flows.

Since this braking current 182 is applied to the saturable reactor SCT in the opposite direction to IB, the saturable reactor SCT operates, and thereafter the conduction rate of the chopper CH is minimized by the same operation as described above.

The above is an explanation of the case where the output signal of the one-shot circuit OS overlaps with the reference pulse signal BP, but since the output signal of the saturable reactor SCT is temporally unrelated to the reference pulse signal BP, the output signal of the one-shot circuit OS overlaps with the reference pulse signal BP. The output signal may not overlap the reference pulse signal BP.

In such a case, the output signal of the one-shot circuit OS is subtracted (since the reference pulse signal BP is zero, the collector voltage VcE4 of the transistor Tr4 is
It is applied to the off-pulse conversion circuit 0fPT via the off-pulse conversion circuit 0fPT, and its rising edge is converted into a pulse to become an off-gate signal.Thereafter, the conduction rate of the chopper CH is minimized by the operation of the same machine as described above. The above operation is repeated to control the braking current IB in accordance with the current command IP.

Next, when the gate start signal GS is turned off, the transistor Tr of the one-shot circuit OS is turned off, and the transistor Tr of the one-shot circuit OS is turned off.
2 turns on.

First, when the transistor Tr is turned off, its collector voltage Vc8 is applied to the resistor R.

Since the reference pulse signal BP is applied to the base of the transistor Tr3 through the reference pulse signal BP, Tr3 is turned on and the reference pulse signal BP is bypassed. Further, when the transistor Tr2 is turned on, its collector voltage Vc82 becomes zero, so the control device CE is locked and the phase control signal PSS is narrowed down.

On the other hand, the collector voltage Vc8 of the transistor Tr is applied to the collector of the transistor Tr4 via the resistor R,4, while the reference pulse signal BP is applied to the base of Tr4 via the resistor R,2. Therefore, the collector voltage V
cE4 becomes as shown in FIG. The collector voltage Vc84 of this Tr4 is applied to the off-pulse conversion circuit 0 through the diode Dd3, and is converted into a pulse to be converted into a pulse.
Since the current is added to the current, the flow rate of the chopper CH is minimized.

Then, when a certain period of time elapses after the gate start signal GS is turned off, the delay circuit TD is turned off, so that a signal whose phase is inverted from that of GS is output.

Since this phase-inverted signal of GS is applied to the base of the transistor Tr4 via the resistor R,3, Tr4 is turned on, and the input signal to the off-pulse conversion circuit PT disappears. As a result, the off-gate signal ■○ and the on-gate signal G disappear, so the chopper CH stops.

As described above, in another embodiment of the present invention, a one-shot circuit is used, which becomes operable when a gate start signal is applied, and does not operate unless the output signal of the saturable reactor is applied in this state. This method subtracts a reference pulse signal corresponding to the commutation period of the chopper from the output pulse of the circuit, converts the signal into a pulse, and uses it as an off-gate signal, minimizing the current flow rate of the chopper. Even if the chopper operates at such timing, continuous gate signals are not applied during the commutation period of the chopper, so the chopper does not fail in commutation, and the element can be prevented from being destroyed. Furthermore, since the one-shot circuit can convert a narrow input pulse into a wide pulse, it also has the advantage that the saturable reactor can be made smaller. As described above, according to the present invention, in vernier power generation braking control of a DC motor using a chopper,
It is possible to provide a chopper control device that can stably and reliably narrow down the chopper conduction rate when a short circuit occurs in the dynamic braking resistor.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram of a conventional chopper control device, Fig. 2 is a circuit diagram of the same according to an embodiment of the present invention, Fig. 3 is a time chart thereof, and Fig. 4 is an electric circuit of another embodiment according to the present invention. FIG. 5 is a time chart thereof. CE: Control device, CH: Thyristor chopper, BP: Reference pulse signal. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A DC motor, a plurality of sections of dynamic braking resistor connected to this motor, a chopper connected in parallel to one section of the dynamic braking resistor, and a contactor connected in parallel to another section of the dynamic braking resistor. , means for generating a current command, means for detecting the current of the motor, means for controlling the conduction rate of the chopper according to the deviation between the current command and the detected current, and the conduction rate or its equivalent. means for turning on the contactor in response to the signal reaching a predetermined value; means for generating a conduction rate narrowing command signal when the contactor is turned on; and means for generating a pulse width corresponding to the commutation period of the chopper. The conduction rate control means includes means for generating a reference pulse signal that is repeated at the operating frequency of the chopper, and an exclusive OR gate that inputs the conduction rate narrowing command signal and the reference pulse signal. Generating an off-gate signal for the chopper in synchronization with the rise of the output signal of the exclusive OR gate, and inhibiting output of a phase-controlled on-gate signal to the chopper while the output signal of the exclusive OR gate is present. A chip control device characterized in that it is configured as follows.