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a. Coil select sensor
H1, 2, 3 are the magnetism sensitive elements (Hall element) used to determine the polarity of the main flux generated when the rotor rotates,
producing the coil conduction select signal.
b. Coil select control circuit
The coil select signal (weak analog value around 2.5V)produced by H1, 2, 3 is converted into the HIGH/LOW level judgement signal in the IC1. The
table below shows the logic diagram of IC1.
Code
HA+
HA–
HB+
Input
HB–
HC+
HC–
UH
VH
WH
Output
UL
VL
WL
c. Motor driver circuit section
Q1 ∼ 6 form the bridge circuit to supply power to the motor coils (U, V, W phase). Q7 ∼ 9 are pre-drivers of Q4 ∼ Q6. The ON/OFF timing of Q1 ∼ Q6
is the output section of the logic diagram of IC1 in b. (refer to above diagram) ON when HIGH. I3 1 ∼ 3 pins control the motor speed by turning
ON/OFF Q4 ∼ Q6 with output signals (uH) from the IC1 and PWM signals outputted from the CPU.
d. Pulse signal (PLS) generating circuit
When the magnet passes the PWB pattern just below the rotor, an induced voltage of sine waveform is generated across the pattern. This is a
minute voltage sine waveform, and is amplified by IC2.2 and formed by IC2.1 into the pulse waveform.
e. PWM signal generating circuit
The CPU compares the PLS signal with the reference CLK generated in the CPU to generate the PWM signal. When the speed of the PLS signal is
greater than the reference CLK, it is judged that the motor is rotating at a higher speed than the specified speed. In that case, the PWM signal duty
ratio is decreased to decrease the speed. When the PLS signal is slower than the reference CLK, is judged that the motor is rotating slower than the
specified speed. In that case, the PWM signal duty ratio is increased to increase the motor speed.
+5V
R61
10K
47
P10
72
P21
Pin No.
1
18
H
17
L
16
L
15
H
14
L
13
H
7
L
8
L
9
H
12
H
11
L
10
L
13
12
1
IC8-6
IC13-1
R62
1.0K
C8
1000pF
GROUND
HMOT drive circuit
2
3
H
L
L
H
H
H
L
L
L
L
H
H
L
H
L
L
H
L
L
L
H
H
L
L
+5V
2
+5V
R63
10K
C9
1µF
GROUND
11 – 5
4
5
L
L
H
H
L
L
L
H
H
H
L
L
H
L
L
H
L
L
L
L
L
L
H
H
DC2 4V
1
DC24V
CN5-1
2
PG
CN5-2
3
HMOT_SIG
CN5-3
4
DC5V
CN5-4
5
HMOT_CLK
CN5-5
C10
10µF
Control PWB
6
L
L
L
H
H
L
L
H
L
H
L
L
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