JPH02136095A - Drive circuit of motor - Google Patents

Abstract

PURPOSE:To reduce electromagnetic noise while suppressing reactive power by driving a plurality of motor drive transistors such that the transient state of motor drive transistors for adjoining phases laps over for a predetermined time between the conducting period and the non-conducting period of the transistor. CONSTITUTION:Sensor signals HU<+>, HU<-> having 180 deg. phase difference are fed to the bases of transistors(Tr) Q7, Q8. Assuming currents flowing through TrQ7, Q8 are I7, I8 and base-emitter voltages thereof are VBE7, VBE8, they satisfy formula 1. Maximum value of current flowing through the TrQ7, Q8 is the current value I0 of a power source CS1. Current flowing through a TrQ9 has maximum value 2XI0 when the current I0 flows through both V-shape transistor Q15 and the TrQ7. A power TrQ4 is driven by half-wave drive current flowing through a TrQ1 and feeds current to three-phase input U. By such arrangement, reactive power can be suppressed sufficiently when the phases are switched and counter electromotive force and electromagnetic noise are also suppressed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a multiphase AC current drive type motor drive circuit, and in particular, to absorption of back electromotive force generated when switching between phases and reduction of electromagnetic noise. It is related to.

[Conventional technology]

FIG. 3 is a circuit diagram of a conventional three-phase motor drive circuit. Three sets of sensor signals (H4, To1 ->, (HV+, To(ヮU) and (+-1, H')) from sensors not shown are input to each positive and negative input terminal of the comparators Δ1 to A3, respectively. be done.

The output of comparator A1 is input to AND gate G4,
It is also connected to the input of AND gate G6 via inverter Q3. The output of comparator A2 is AND gate G
5 and to the input of AND gate G4 via inverter G1. The output of comparator A3 is A
It is connected to the input of ND gate G60 and to the input of AND gate G5 via inverter G2.

The outputs of the AND gates G4 to G6 are respectively connected to the bases of N P N + transistors Q to Q3 whose emitters are grounded. The collectors of the NPN transistors Q1 to Q3 are power transistors Q to Q for driving the motor.
6 bases, respectively.

The emitters of power transistors 04 to Q6 are voltage sources ■.

0, the collector is connected to the three-phase input U of the motor
, V, and W, respectively. The three-phase inputs U, V, and W are commonly connected through a coil and grounded. Further, a large capacitance external capacitor C for drive current integration and a resistor R1 are connected in parallel between the base and emitter of the power transistor Q4. Similarly, a capacitor C, a resistor R, a capacitor C3, and a resistor R3 are connected between the bases and emitters of the power transistors Q and Q6, respectively.

Next, the operation will be explained. In FIG. 3, it is assumed that the state of the sensor signal is HU+>HU and HV<H-.

The output of the comparator Δ1 becomes "H" level. The output of comparator A2 is at the "high" level and the output of inverter G1 is
The output of AND gate G4 becomes ``H'' level. The output of AND gate G4 becomes II HIT level, and transistor Q1 becomes conductive. Power transistor Q4 becomes conductive and is driven, and the three-phase input U becomes ``H''. level. Similarly, H">H-and H)<H buttock V
When VW, the power transistor Q is driven, and when H+>H and H, the power transistor Q6 is driven when it is <H, and the three-phase inputs v and W are respectively at the it H++ level.

FIG. 4 shows sensor signals H,+, and T1. HvH, H14+
, H and three-phase inputs u, v.

■ - It is a timing chart showing a waveform with respect to the rotation angle of the W motor. The sensor signals HU+ and HU11 and H- and HW+ and H- have a phase difference of 180° in ν, respectively. Also, the sensor signal H
, HV+ , + are 120 degrees apart from each other
・Has a phase difference of H. The sensor signals H11''ヮH,- also have a phase difference of 120 degrees from each other.

Therefore, the three-phase inputs U, V, and W are 1 in the order of U → V → W.
Electricity is applied every 20 degrees of rotation angle.

In motor drive using such pulses, reactive power is reduced, but the rise of each pulse.

At the time of falling, the magnetic field inside the motor changes sharply and a back electromotive force is generated.

[Problem to be solved by the invention]

Since the conventional motor drive circuit is configured as described above, there is a problem in that a back electromotive force is generated when switching each phase of the three-phase input U, V, and W, and electromagnetic noise is likely to occur.

Furthermore, if large-capacity external integrating capacitors C, C, and C3 are provided to absorb this back electromotive voltage, there is also the problem that the entire device becomes larger.

This invention was made to solve the above-mentioned problems, and uses a large-capacity external integrating capacitor to reduce the back electromotive force generated when switching each phase while suppressing the increase in reactive power. It is an object of the present invention to obtain a motor drive circuit that suppresses electromagnetic noise without using it, reduces electromagnetic noise, and reduces the size and weight of the entire device.

(Means for Solving the Problems) A motor drive circuit according to the present invention has a plurality of motor drive transistors arranged in a multiphase configuration in an output stage, the output of which is connected to the plurality of motor drive transistors, It has an output for driving the plurality of motor drive transistors such that the overconcentration states between the conduction period and the non-conduction period of the motor drive transistors of adjacent phases among the plurality of motor drive transistors overlap for a predetermined period of time. It is equipped with a control circuit.

[Operation] The sub-circuit in this defense is configured to control a plurality of motor drive transistors so that the transient states between the conduction period and the non-conduction period of the motor drive transistors of adjacent phases overlap for a predetermined period of time among the plurality of motor drive transistors. Drive the drive transistor.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a circuit diagram of a three-phase motor drive circuit according to an embodiment of the present invention. First, the configuration of the U phase will be explained.

Transistor Q7 configuring the differential amplifier. Sensor signals HU+ and HU- are respectively input to the base of Q8.

The emitters of transistors Q and Q8 are commonly connected and have a current capacity f! It is grounded via the current source C81 of iIo. The collector of transistor Q7 is connected to the collector of transistor Q9, whose base and collector are connected. The bases of transistor Q and transistor Q1o are connected,
The emitter is also a voltage source V. Commonly connected to 0. Transistor Q9. Qlo constitutes a current mirror. Transistor Q9. The base of Qlo is also connected to the collector of the V-phase transistor Q (corresponding to the U-phase transistor Q8).

The collector of transistor Q1o is connected to the collector of transistor Q11. The base of transistor Q11 is connected to the base of Q12, whose base and collector are connected. The collector of the transistor Q12 has a current capacity I
are connected to voltage source V through current source C84 of transistors Q11. Q12 C Mitter is grounded. Transistor Q11. Q12 constitutes a current mirror.

The collector of transistor Q11 is connected to the collector of transistor Q13 whose base and collector are connected. The base of transistor Q13 is connected to the base of transistor Q1, and the emitters of transistors Q1 and Q13 are grounded. Transistor Q1. Q13 is Karen l-
It constitutes a mirror.

The collector of transistor Q1 is power transistor Q4
connected to the base of The emitter of the power transistor Q4 is connected to the voltage source vcc, and the collector is connected to the three-phase input U of the motor.
connected to. Further, a resistor R1 is connected between the base and emitter.

The other V and W phases also have similar configurations as shown below. The U-phase transistor 01 corresponds to the ■-phase transistor Q2 and the W-phase transistor Q3, respectively. The U-phase transistors Q7 to Q13 are the ■phase transistors Q14 to Q2o, and the W-phase transistor Q21.
〜Q2□, respectively. The U-phase power transistor Q4 corresponds to the ■-phase power transistor Q5 and the W-phase power transistor Q6, respectively. Also, U phase current sources C31, C34t, t, V phase f7) W flow yic
s2. cs5r! 3 and W phase current ics, cs6
The U-phase resistor R1 corresponds to the V-phase resistor R2 and the W-phase resistor R3, respectively.

As mentioned above, the U-phase 1-transistor Q9. In the same way that the base of Q1o is connected to the collector of V-phase transistor Q15, V-phase transistor Q16. Q17
The base of and the collector of W-phase transistor Q22 are
W-phase transistor Q23. The base of Q24 is connected to the collector of the phase transistor Q8. Further, the collector of the ■-phase power transistor Q5 and the three-phase input (■) of the motor are connected, and the collector of the W-phase power transistor Q6 and the three-phase input W of the motor are connected, respectively. The three-phase inputs UV and W are commonly connected through a coil and grounded.

Next, I will explain the operation. Here, U shown in FIG.
The operation of the phases will be explained. Transistor Q7 forming a differential amplifier. Sensor signals HLI+HII having a phase difference of 180° are input to the base of Q8. The currents flowing through transistors Q7 and Q8, respectively!
7. I8, and the base-emitter voltage is V,■
Then, BF2 8E8 The following equation (1) holds true.

q/kT 1 /I −ε (V −V )...
(1) 7 8 8E7 BF8 Also,
Transistor Q7. The maximum value of the current flowing through Q8 is the current 1a I o of current source C81. The current flowing through the transistor Q9 is a current (■) in both the transistor Q15 and the transistor Q7 of the ■phase. When flowing, the maximum value is 2X
Io yells. Transistor Q9. Qlo forms a current 1-mirror, and the maximum value of the current '10 flowing through the transistor Q1o is also 2×■o.

Current '10 flows through transistor Q11. In the current mirror formed by Q12, the current value I. is pulled out. As a result, transistor Q13. The maximum value of the current supplied to the current mirror of Q1 is the current value I. bawl.

Furthermore, in the above current conversion, the rise and fall of each current change exponentially according to the waveform shown in equation (1).

Power transistor Q4 is driven by the half-wave drive current flowing through transistor Q1 and supplies current to three-phase input U. Similar operations occur for the other V and W phases.

Figure 3 shows sensor signals H, H, Hv U 1-(-, H", H,- and three-phase inputs U, V.

3 is a timing chart showing waveforms with respect to the rotation angle of WW.

In FIG. 2, for example, the period T of the three-phase inputs U, V, W
During the rising period of the V phase and the falling period of the U phase such as 1, the three-phase inputs U, V, and W change exponentially.

During that period, the three-phase inputs U, V, W have quasi-linear trapezoidal waveforms that overlap each other with respect to adjacent phases. Therefore, the reactive power at the time of switching each phase can be sufficiently reduced, and the back electromotive voltage and electromagnetic noise generated at the time of switching are suppressed.

In the above embodiment, a circuit using a PNP type power transistor was described, but the present invention can be similarly applied to a circuit using an NPN type power transistor. Further, the present invention can be applied to two-phase or other multi-phase motor drive circuits other than three-phase, and can be similarly applied to motor drive circuits of a reciprocating energization type.

(Effects of the Invention) As described above, according to this J-mei, the control circuit controls the transient state between the conduction period and the non-conduction period of the motor drive transistors of adjacent phases among the plurality of motor drive transistors. Since multiple motor drive transistors are driven in a timed manner, the increase in reactive power is suppressed, and the back electromotive force generated when switching each phase is suppressed without using a large-capacity external integrating capacitor. Therefore, it is possible to obtain a motor drive circuit that reduces electromagnetic noise and makes the entire device smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a three-phase motor drive circuit according to an embodiment of the present invention, FIG. 2 is a timing chart showing waveforms of each part of the motor drive circuit, and FIG. A circuit diagram of the drive circuit, FIG. 4 is a timing chart showing waveforms of various parts of the motor drive circuit shown in FIG. 3. In the figure, Q, Q5. Q6 is a power transistor. In addition, the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa Diagram procedure correction amount (voluntary)

Claims (1)

[Claims] (1) A motor drive circuit having a plurality of motor drive transistors arranged in a multiphase configuration in an output stage, the output of which is connected to the plurality of motor drive transistors, and an adjacent one of the plurality of motor drive transistors. A motor drive circuit comprising: a control circuit having an output for driving the plurality of motor drive transistors such that transient states between conduction periods and non-conduction periods of the motor drive transistors of phases overlap for a predetermined period of time.