JPS5869118A - Switching amplification system - Google Patents

Abstract

PURPOSE:To decrease power consumption with a miniazurized and light weight device, by preventing transistors of output stage of positive and negative power supplies from being simultaneously turned on, in switching a load from one to the other power supply driving. CONSTITUTION:In a control circuit CC2, a designation signal VS2 applied to its input terminal B2 regulates the polarity of power supply driving a motor M2 and the amplitude is adjusted to control a motor current IL2. When the signal VS2 is positive, the motor is driven with a negative power supply and when negative, the motor is driven with a positive power supply. Thus, in applying a display signal VL2 to an input terminal A2 of the circuit CC2 as it is, the signal VL2 is opposite in the polarity as the signal VS2, and the motor current IL2 is automatically controlled so as to be matched to a designated motor current IS2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switching amplification system, and more particularly to a switching amplification system that uses a switching power amplifier to switch between positive and negative power sources for driving a load.

In various types of control devices, desired control is performed by changing the speed of the motor or changing the polarity of the power source that drives the motor to switch the direction of rotation of the motor. In this case, conventional power amplifiers for driving motors generally use output stage transistors in the active region, or are of a near type.

Currently, the conventional power amplifier for driving this kind of motor is the first one.
This will be explained with reference to the drawings and FIG. In Figure 1, MI
Fi is the motor that becomes the load, IL is the motor current, Re, F
i Load current, that is, motor current detection resistor, PA, linear power amplifier, output stage transistor T
rg, Tri, drive transistor Trt.

Trs, protection diode DI, Di, protection resistance Rx, R
s, Rs.

Bias resistance R,, R snow, 'R4, positive power supply (+Vt)
CCI is a control circuit that generates a control signal V (11) that drives the power amplifier FAI, and includes an operational amplifier OP1 and an external resistor R.
It consists of a control signal slope adjustment capacitor C1 connected in parallel to a feedback resistor R/s. The voltage across the motor circulation detection resistor Rot, that is, the motor current IL, is input to the input terminal A1.
A motor current indicating signal VLI indicating the magnitude of I is applied. Input terminal B1 is connected to a wave phase constant signal (hereinafter referred to as a designated signal) VS that outputs a motor voltage corresponding to the designated motor current S1.
l is applied. Here, the designation signal VS1 and the motor current display signal L1 are selected to have opposite polarities. Therefore, the operational amplifier OP operates as a kind of differential amplifier for both signals.

Next, the operation shown in FIG. 1 will be explained with reference to FIG. 2.

FIG. 2(A) is an operation diagram when there is no slope adjustment capacitor C1 provided in the operational amplifier OF.

If the designation signal V81 is set to a positive level and driven by a negative power supply, the control signal V61 generated from the control circuit CC Sumire becomes a negative output, so that the transistors Trl and Trz are driven by the voltage Vs. Output stage transistor Tr4 (Trz
(Similarly) is a linear amplifier that operates in the active range, so its collector current Fi changes in proportion to the amplitude of the control signal VOI supplied to the base of the transistor Trm for driving it. Since the amplitude of the control signal VOS is proportional to the magnitude of the designated signal S1, the collector current of the transistor Tr, that is, the flow IL, #i of the motor 1 changes accordingly. This relationship holds true for transistor Tr1. The same applies to the case where the motor M is driven by the positive power supply (+V1) through Tr2. In other words, the severity of the specified signal ■S□ defines the severity of the power source that drives the motor M1 (in the case of Fig. 1, the specified signal ■S□
When the polarity of l is positive, it is driven by a negative power supply, and when it is negative, it is driven by a positive power supply.) By adjusting its magnitude, the magnitude of the shimoter current IL1 can be controlled.

Input terminal A*KId of control circuit CC1 motor current IL.

Motor current display signal (hereinafter referred to as display signal) that indicates the magnitude of vL1 may be supplied as is to the input terminal A1 of the control circuit CCI). Therefore, the magnitude of the motor specified current 1Istl>Motor'IILbat l ILI
1, the magnitude of the control signal Vol increases and the magnitude of the motor current ILI increases, and in the opposite case, the magnitude of the control signal VOI decreases and the magnitude of the motor current Ix,1 increases. Decrease size. By feeding back the display signal VLI to the control circuit CC1 in this manner, it is possible to match the magnitude of the designated current Igl and the motor current ILI.

By the way, the circuit shown in FIG. 1 has the following problem. In other words, transistors generally have a property that the delay time when they turn from on to off is longer than the delay time when they turn from off to on.

Now, when the designation signal VS switches from reconnaissance power supply drive to positive power supply drive at time To in Figure 2 of the Imperial Decree, the control signal Val
As shown in the second figure), at time To, the shell changes in a step-like manner. Corresponding to this, Fig. 2 (61,
(As shown in cl, transistors Trs and Ill, ,
changes from on to off, and the transistors Tr1 and Trz
changes from off to on. And the time from when Trs and Tr4 turn on to off is Torp, Trt and Tr
If the time from OFF to ON of Z is f TON, then TOFF > TON. Therefore, from TON to T
During the OFF dark period, the transistors Tr2 and 1t4 are simultaneously on. As a result, the positive power supply (+Vt) and negative power supply (-Vl) are short-circuited by transistors Tr2 and 'fr4, and even if the period is short, a large current flows and thermally destroys transistors 1'r2 and Tr4. Otherwise, it will have an adverse effect on the positive and negative power supplies.

In order to solve this open circuit, in the conventional device, as shown in FIG. 1, a slope adjustment capacitor C1 is differentially connected to the feedback resistor Rfs of the operational amplifier OF.

As a result, the operational amplifier OP operates as an integrator, so the control signal VO1 transmitted from the control circuit CC1 is
As shown in (d) of FIG. 2(B), the characteristic increases from negative to positive at a constant slope from time To. When the pace-emitter saturation voltage VBIIK of the transistor Trs is reached at time T1, as shown in FIG.
The operation of OFF-＼ starts from ON to OFF-＼, and the time TOFF
It turns off at . When the control signal Vol reaches the pace table emitter saturation voltage VBIJK of the transistor Tr1 at time T2, as shown in FIG. 2 (1), both the transistors Tr1 and Tr2 are turned off.
The operation from tame to o/ is started and turns on at time TON. In this case, since the transistor Tr4 is already off when the transistor Tr2 is turned on, no short circuit will occur between the positive power source (+V1) and the negative power source (-Vl). The same applies to the operation of switching from positive power supply drive to negative power supply drive.

Generally, in order to see that the transistors Tr2 and Tr4 in the output stage are turned on at the same time, it is necessary to
The maximum rate of change V8LVO1 (volts 7 seconds) is the second
From Figure [I3], it is as follows.

, , , , , ,VnB1+V昂目*, ,M7),
, >y 8LvO, (pol) 7)) where TON
(Tri-): Time from when Trl is turned on to when Tra is turned on; Topr (Trs, n): Time from when Trs is turned off to when Tri is turned on.
This is the time until it turns off.

The desired rate of change of the control signal Vl)j is then determined by varying the size of the slope gfiF adjustment capacitor C1.

In this way, the problem of transistors Tr2 and Tr4 being turned on at the same time has been resolved, but since the power amplifier FAI of the conventional device is of the y=near type in which the output stage transistors Tr2 and Tr4 operate in the active region. Additionally, there were problems such as high power consumption, large heat dissipation structure due to large amount of heat generation, and inability to downsize the entire device.

Therefore, in order to improve such problems, the present invention has the following features:
This prevents the output stage transistors on the positive and negative power supply sides from turning on at the same time even when the load is switched from one power source drive to the other power source drive, and has a simple heat dissipation structure with low power consumption. An object of the present invention is to provide a switching amplification method for driving positive and negative power supplies, which can reduce the size of the power supply and make the entire device lightweight and compact. For this purpose, the switching amplification system of the present invention includes a first switching amplification means that supplies an output to the load from a positive power supply, and a second switching amplification means that supplies an output to the front load from a negative power supply. means for generating a control signal that changes at a slope of a predetermined rate of change when switching between positive and negative power supply drives, and means for generating first and second reference signals each having a dead zone of a predetermined level; a first comparison means for comparing the side (2) signal and a first reference signal to drive the first switching amplification means; a second comparison means for driving the switching increase means;
The present invention is characterized in that the switching amplifying means of 1 and the switching amplifying means of #f2 are not turned on at the same time when switching between positive and negative power supply drives.

An embodiment of the present invention will be described in detail below with reference to FIGS. 3 to 5.

FIG. 3 shows the configuration of an embodiment of the present invention, and FIG.
FIG. 5 is an explanatory diagram of the operation.

In the figure, Ml is the motor that is the load, IL2 is the motor current,
R02 is a load current (motor current) detection resistor, P
4 tr, r A transistor Try in the output stage that performs switching operation in a switching power amplifier.

Tra, m-transistors Trs, Trγ, protection diodes IJs, Da, protection resistors R9, R11, bias i anti-Rto, Ih2°#t3. jtn, JE'
dt source (+Vx) & negative #hl (Vx). CPl and CF2 are comparators consisting of differential amplifiers, R2O is a reference signal generator, operational amplifier OPl and external resistor R1! l, R16, R17, R11
It consists of an inverting amplifier circuit consisting of 1, and one input terminal E has an I%'+? The r signal vr is applied, and the other input terminal F is supplied with the sawtooth signal SW for reference. I
The N/I'i inverter is composed of an operational amplifier OF and an inverting amplifier consisting of external resistors Rte, Rzo, and R2. cc2 is the control signal ν0! similar to the control circuit CC1. The control circuit that generates the operational amplifier OP3,
The external components consist of a resistor 11h2゜R base, Rm, a feedback resistor Rf', and a capacitor at for adjusting the slope of the control signal. The display signal ■L weight is applied, indicating that the other input terminal B! Specified motor area IS! The specified signal vS! is a voltage corresponding to is transmitted.

Here, the command signal ■Sz and the display signal VLs are selected to have opposite polarities.

First, the dead band 1g signal Vrg/
is not supplied, the output stage transistor Tt.
The operation and problems when the Tr8 and Tr8 are used as a simple VC switching type power amplifier will be explained with reference to Figure 4.

“Hou” control circuit CC! is the specified signal ■S! supplied to its input terminal B, similar to f[ilJ control circuit CC,. defines the polarity f of the llr source that drives the heptad M2, and controls the magnitude of the shimotor current IL by adjusting its amplitude 'gA, and the designated signal vS2 is When the polarity is positive, it is driven by a negative electric current, and when it is negative polarity, it is driven by a positive power supply. As a result, in the circuit configuration of FIG. 3, i- is input to the display signal VL, and input terminal A of the control circuit CC is input as is.

If supplied to Vζ, it will have the opposite polarity to the designated signal VSz,
Automatically controlled to match. A control signal Vow Vi generated from the control circuit CC2 as shown in FIG. 4(a) is supplied to one input terminal of the comparator CP5CPi.

The single tooth wave SW supplied to the input terminal PK of the reference signal generator RAG is inverted and amplified to become the sawtooth reference signal Vrsg2 shown in FIG.
is supplied to one or both input terminals. Some others are invar
The saw 1 shown in FIG. 4 (6) is further inverted by IN.
The waveform reference signal Vr8g1 is then supplied to the other input terminal of the comparator CP.

Now the designated signal ■S! The positive pole of is positive, that is, the control signal Vo
, the polarity of is negative, negative power supply (-Vg) K and motor M
For example, the magnitude of motor current t-
The operations to be controlled will be explained.

The amplitude of control #J signal Vat (i.e. motor designation signal VS
The amplitude of H) is as shown in Figure 4 (6) (A).
In this case, during the time l1lcL from time T8m until the reference signal VrBgz reaches Uα, the comparator CP generates a negative voltage, turns on the drive transistor Try and the output stage transistor Tra, and turns on the negative power supply (-V). motor M2'? - Drive. Similarly, the transistor Tr- in the output stage is turned on for the time from zero level to U for each tooth-like wave of 5 minutes of the reference signal Vrsg2, and the motor Pvh K current is supplied. Therefore motor M
2, a current flows for a predetermined period every cycle of the reference signal Vr8g*.

In the linear system shown in Figure 1, the power amplifier Pall is used as a power amplifier. L”
The motor current flowing continuously in proportion to the amplitude e of the signal Vot was controlled by taking into account the magnitude of the motor current L1, but in the switching method, the circle; Although the instantaneous magnitude of the motor current IL2 remains unchanged due to a change in amplitude, the magnitude of the motor current IL2, that is, the magnitude of the average current, is controlled by changing its conduction time. In FIG. 4(b)(a), the control signal VO2 is UOK.
When N is added, the on period of the transistor Tt- in the output stage increases to FiTo, and the energization time of the motor tAfIL2 also increases, and its average value becomes large. Conversely, the control signal V
If the amplitude of ow decreases to U6, the on period of the transistor Tr- decreases by T6 K, so the conduction time of the motor current L2 also decreases, and its average value becomes smaller. In this way, the magnitude of the motor current L2 is controlled in proportion to the magnitude of the control signal Vow, that is, the designation signal Vat. If the polarity of the designated signal v8 is made negative, the polarity of the control signal O1 becomes positive.The driving transistor Trs and the output stage transistor Tr- are turned on, and the motor M2 is driven by the positive power supply (+V). However, the operation in this case is the same as in the case of negative power supply drive. Although the magnitude of the saturation voltage of each transistor has been ignored for the sake of simplicity, the operation is the same as described above even if the existence of the saturation voltage is taken into account. When fed back to A3, since the polarity of the designated signal 78 is opposite to the polarity of the designated signal 78, the on-period of the output stage transistor Trl is controlled to decrease when lVL 1 > lV8*l, and lV
L*l < IV8! When the output stage is 1, the on period of the output stage transistor Try is controlled to increase, and the motor current 1L is automatically controlled to match the specified motor current Itg.

Next, we will first explain the operation when switching from negative power supply drive to positive power supply drive and the interstate point that exists in that case. There will be a break between songs in case the song is not available.

Now, when the amplitude of the control signal Vow is Ud shown in FIGS. 4(h) and (b), the output stage transistor Tr-
ON only from sz to Td l), Td(!: T8s
period is off. Therefore, even if the negative power supply drive is switched to the positive power supply drive during the period Td and Tag, the problem that the transistors Tr@ and Tr@ are turned on at the same time does not occur. However, when switching at time T# near Td, the transistors Ty@, Trs
It turns on simultaneously between u times T/ and Tg. This situation!
The same holds true for @#'iT* and >Td. Therefore T8! If the switching occurs in a time slightly longer than 'rd and 'rd, a problem will occur in the switching method as well, in that the output and power stage transistors Tr and TI will be turned on at the same time.

Next, a slope adjustment capacitor Cs is connected to the feedback resistor R/2. Output stage transistors T r a , T r
The case in which s are most likely to turn on at the same time is when the transistor Trl switches at time Tss when it turns on. If the negative power supply drive is switched to the positive power supply drive at time TS3, the control signal Vo
w is the capacitor C for tilt adjustment from time Ts3! This causes the transistor 'l'rs to rise with a slope defined by the control signal o8 and the reference signal Vraσ2.
At the time TA [where the values coincide with each other, the on-to-off operation starts, and the switch turns off at the time Tj.

On the other hand, the transistor Tr- is connected to the control signal Vow and the reference signal V.
The operation starts from off to on at time Tj when the rsgs match, and turns on at time T&. Therefore, the transistors Tr@ and Tr- are turned on simultaneously during the time period Tk and Tj. This state does not change even if the on/off times of the driving transistors Trs and Try are taken into consideration. In this way, in the switching method, like in the linear method, the slope ′v! 4 Adjustment capacitor C
! The problem of transistors Tr+ and Trs in the output stage being turned on at the same time cannot be solved by means of providing a sawtooth waveform of the reference signal. Dead zone? In the present invention, the reference signal is a sawtooth wave with fixed level dead band voltages Vftx, Vm2 ii - Vsgx' added to the sawtooth wave, which will be explained based on the operation diagram shown in FIG.
, VJ7'. Now in Fig. 5, time T51
When the negative power supply drive is switched to the positive power supply drive at 2', the transistor Tr8 receives the control signal Vow and the reference signal Vsg*.
It starts turning from on to off at time T h/, which is one month after '', and turns off at time T s/. On the other hand, the transistor Tr4 receives the control signal Vo2 and the reference signal Vsgx.
It starts to turn on from OFF at time T/ when ' coincides with it, and turns on at time T&'. However, in this case, since #'iTk' is 6/, the transistor Tr-
Since the transistor Tr8 is already turned off when the transistor Tr8 is turned on, the situation M in which the transistors TI and Tr@ are turned on at the same time does not occur.

Note that the dead band voltage V%"mV%N is the saturation voltage Vtv s of the driving transistors Trs and 'l'ry, respectively.
It is necessary to make the output stage transistor Tr.larger than Vivy.

In order to avoid Trs from turning on at the same time, the maximum value of the rate of change of the control voltage VsLvoz (volts 7 seconds) is as follows from FIG.

Here, ToN (s, s): After Tri is turned on, Tr・
Time until TOFF(7,11) turns on: The rate of change of the control signal Vow resulting from the time from when Trl turns off to when Trl turns off adjusts the size of the capacitor C for adjusting the slope aMl. It is often done.

Furthermore, the control of the magnitude of the motor current IL is shown in Figure 5 (6).
1, similarly to the above, the control @signal ■mouth size ζ, that is, the designated signal Va! By changing the size of 08"JUllII, the on period of the output stage transistor is set to a4
This is done by warning.

In addition, the display signal VLZ is fed back to control the motor current I.
The control operation to match Lz with the specified motor radio wave I8z also has a non-Ie band pressure ■1%1. There is no change due to the provision of v1. Due to this feedback control operation, the switching amplification operation is also performed stably.

Although the above explanation has been made based on negative power supply driving, the same applies to positive power supply driving.

Next, the non-g charging voltage Vn1. The configuration for adding Vs2 f will be explained in FIG.

Input terminal E of reference signal generator R8O [dead band voltage Vn(
= Vnl-Vaz)
When supplied, a desired reference signal VrBgj is generated at the output terminal of the inverter IN, and a reference signal VrBgj is generated at the output terminal of the inverter IN.
8 g 1' occurs. If reference 4m No. Vrsgt
When it is necessary to set the dead band voltage levels of ' and VrBgg to different values, for example, the return M resistance R of the inverter IN
20 or the values of r and tRt* may be adjusted.

As explained above, according to the present invention, it is possible to reduce the power consumption of the spot power amplifier by using a stable switching method, and also to apply the reference signal ζf of the i/C1 insensitive # voltage? In use, it is possible to prevent the output stage transistor from turning on at the same time when the IMA dynamic power supply stops or goes negative, and can be controlled simply by adjusting the value of the 1 yen, g + A adjustment capacitor. You can change the rate of change of the Igi number.

[Brief explanation of drawings]

'@ Figure 1 is a conventional linear type power amplifier, Figure 2 is an explanation diagram of its operation, Figure 3 is a configuration diagram of an embodiment of the switching system of the present invention, and Figures 4 and 5 are explanations of its operation. It is a diagram. In the figure, M1. Mx is a motor, PAI is a linear type power multiplier, PA is a switching type power amplifier, and Ccl. What about CC2? 1III control circuit, IN is inverter, R8G
Fi reference signal reference device, CPS, CPS is comparator, Trl
~Trsu) transistor, UPl~OPm are operational amplifiers, CI, C, are capacitors, RCI, RC*
is the motor current detection resistor, VOI. Vo2 is a control signal, VLt, VLx are motor current display signals, Vst, Vsl are motor current designation signals, SW is sawtooth wave No. 4g, Vrsgw, Vrsg2. Vragl'
, Vragz' indicate #respective signal, respectively. %Kanto Hariyama, Fujitsu Taipei company representative patent attorney, Koei Yamatani 1 g (-) -''rzm ts Figure 1

Claims (1)

[Claims] (1) A first switching amplification means that supplies an output to the load from a positive power supply, a second switching amplification means that supplies an output to the load from a negative power supply, and a first switching amplification means that supplies an output to the load from a negative power supply; control means for generating a control signal that changes with a slope of a predetermined rate of change; means for generating first and second reference signals each having a dead zone of a predetermined level; a first comparison means for driving the first switching amplification means; and a second comparison means for comparing the control signal and a second reference signal to drive the second switching amplification means. A switching amplification system characterized in that the first switching amplification means and the second switching amplification means are prevented from being turned on at the same time when switching between positive and negative power supply drives.